EP0758760A1 - Zweiseitigbeschichtete radiographische Elemente enthaltend Emulsionen mit tafelförmigen Körnen, die verbesserte Bindemittel enthalten - Google Patents

Zweiseitigbeschichtete radiographische Elemente enthaltend Emulsionen mit tafelförmigen Körnen, die verbesserte Bindemittel enthalten Download PDF

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EP0758760A1
EP0758760A1 EP96202226A EP96202226A EP0758760A1 EP 0758760 A1 EP0758760 A1 EP 0758760A1 EP 96202226 A EP96202226 A EP 96202226A EP 96202226 A EP96202226 A EP 96202226A EP 0758760 A1 EP0758760 A1 EP 0758760A1
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starch
emulsion
tabular grain
cationic
grains
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EP0758760B1 (de
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Joe Edward C/O Eastman Kodak Co. Maskasky
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Eastman Kodak Co
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    • 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
    • G03C1/00—Photosensitive materials
    • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
    • G03C1/04—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with macromolecular additives; with layer-forming substances
    • 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
    • G03C1/00—Photosensitive materials
    • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
    • G03C1/0051—Tabular grain emulsions
    • 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
    • G03C1/00—Photosensitive materials
    • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
    • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
    • G03C1/08—Sensitivity-increasing substances
    • G03C1/10—Organic substances
    • G03C1/12—Methine and polymethine dyes
    • 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
    • G03C1/00—Photosensitive materials
    • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
    • G03C1/46—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein having more than one photosensitive layer
    • 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
    • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
    • G03C5/16—X-ray, infrared, or ultraviolet ray processes

Definitions

  • the invention is directed to an improvement in radiographic elements. More specifically, the invention is directed to radiographic elements that employ high bromide ⁇ 111 ⁇ tabular grain silver halide emulsions.
  • radiographic element refers to an element intended to record a pattern of X-radiation. This includes indirect radiographic elements that rely on an intensifying screen to absorb X-radiation and emit a corresponding pattern of light for recording by the radiographic element.
  • dual coated refers to radiographic elements that contain image recording units on opposite sides of an X-radiation transmissive support.
  • dual coated radiographic elements are quite different than "double coated” or “triple coated” photographic elements that contain multiple silver halide emulsion layers on a single side of a support.
  • ECD equivalent circular diameter
  • tabularity is defined as ECD/t 2 , where ECD and t are both measured in micrometers ( ⁇ m).
  • tabular grain indicates a grain having two parallel crystal faces which are clearly larger than any remaining crystal face and having an aspect ratio of at least 2.
  • tabular grain emulsion refers to an emulsion in which tabular grains account for greater than 50 percent of total grain projected area.
  • high bromide in referring to grains and emulsions indicates that bromide is present in concentrations of greater than 50 mole percent, based on total silver.
  • the halides are named in order of ascending concentrations.
  • ⁇ 111 ⁇ tabular is employed in referring to tabular grains and tabular grain emulsions in which the tabular grains have ⁇ 111 ⁇ major faces.
  • hydrophilic colloid vehicle and “vehicle” refer to the hydrophilic colloid peptizers and binders present in silver halide emulsions.
  • selected vehicle and “selected peptizer” are employed to designate vehicle or peptizer derived from a water dispersible cationic starch.
  • starch cationic in referring to starch indicates that the starch molecule has a net positive charge at the pH of intended use.
  • oxidized starch indicates a starch in which, on average, at least one ⁇ -D-glucopyranose repeating unit per starch molecule has been ring opened by cleavage of the 2 and 3 ring position carbon-to-carbon bond.
  • water dispersible in referring to cationic starches indicates that, after boiling the cationic starch in water for 30 minutes, the water contains, dispersed to at least a colloidal level, at least 1.0 percent by weight of the total cationic starch.
  • ddle chalcogen designates sulfur, selenium and/or tellurium.
  • Radiation-sensitive silver halide emulsions employed in radiographic elements are comprised of a dispersing medium and silver halide microcrystals, commonly referred to as grains. As the grains are precipitated from an aqueous medium, a hydrophilic colloid peptizer is adsorbed to the grain surfaces to prevent the grains from agglomerating. Subsequently binder is added to the emulsion and, after coating, the emulsion is dried. The peptizer and binder are collectively referred to as the vehicle of an emulsion.
  • Glue is thus distinguished by its adhesive properties; gelatin by its cohesive properties, which favor the formation of strong jellies.
  • Photographic gelatin is generally made from selected clippings of calf hide and ears as well as cheek pieces and pates.
  • Pigskin is used for the preparation of some gelatin, and larger quantities are made from bone.
  • the actual substance in the skin furnishing the gelatin is collagen. It forms about 35 per cent of the coria of fresh cattle hide.
  • the corresponding tissue obtained from bone is termed ossein.
  • the raw materials are selected not only for good structural quality but for freedom from bacterial decomposition.
  • the dirt with loose flesh and blood is eliminated in a preliminary wash.
  • the hair, fat, and much of the albuminous materials are removed by soaking the stock in limewater containing suspended lime. The free lime continues to rejuvenate the solution and keeps the bath at suitable alkalinity.
  • Gelatin may also be made by an acid treatment of the stock without the use of lime.
  • the stock is treated with dilute acid (pH 4.0) for one to two months and then washed thoroughly, and the gelatin is extracted.
  • This gelatin differs in properties from gelatin made by treatment with lime.
  • Suitable hydrophilic materials include both naturally occurring substances such as proteins, protein derivatives, cellulose derivatives--e.g., cellulose esters, gelatin--e.g., alkali-treated gelatin (pigskin gelatin), gelatin derivatives--e.g., acetylated gelatin, phthalated gelatin and the like, polysaccharides such as dextran, gum arabic, zein, casein, pectin, collagen derivatives, collodion, agar-agar, arrowroot, albumin and the like....
  • This description is identical to that contained in Research Disclosure, Vol. 176, December 1978, Item 17643, IX. Vehicles and vehicle extenders, paragraph A. Research Disclosure is published by Kenneth Mason Publications, Ltd., Dudley House, 12 North St., Emsworth, Hampshire P010 7DQ, England.
  • Patent 4,414,304 discloses radiographic elements containing tabular grain emulsions that are fully forehardened, resulting from the observation that tabular grain emulsions, unlike the emulsions previously employed in radiographic elements, exhibit high covering power characteristics that are minimally affected by increased hardening of the emulsion vehicle. Based on these advantages of dual coated radiographic elements an industry conversion to tabular grain emulsions has occurred.
  • elevated viscosity levels imparted by these peptizers interfere with reactant mixing to obtain uniform grain characteristics.
  • elevated viscosities work against uniform mixing on a microscale (micro-mixing) which is essential for uniform grain nucleation and growth.
  • Nonuniformity in grain nucleation and, to a lesser extent, growth result in grain polydispersity, including the coprecipitation of grains that differ in their shape and size and, where multiple halides are being coprecipitated, their internal distribution of halides.
  • Elevated levels of viscosity work against being able to sustain desired levels of bulk mixing of reactants as the total volume of the reaction vessel is increased.
  • the peptizer polymers being of natural origin, contain mixtures of differing molecules, differing in weight and structure, not all of which are well suited to emulsion preparation. Further, the peptizers exhibit variations based on origin of the starting materials and can vary in composition over time, even when obtained from a single commercial source. Unwanted effects can be seen both in physical properties, such as turbidity, and in sensitometric properties, such as fog.
  • heating of silver halide emulsions is required to achieve chemical sensitization by any one or combination of middle chalcogen (i.e., sulfur, selenium and/or tellurium), noble metal (e.g., gold) or reduction sensitization.
  • middle chalcogen i.e., sulfur, selenium and/or tellurium
  • noble metal e.g., gold
  • reduction sensitization For achieve anywhere near maximum acceptable photographic speeds heating to at least about 50°C is typical, with maximum temperatures being limited only by ambient vapor pressures (e.g., boiling away of the aqueous component). At these elevated temperatures grain ripening is accelerated. This can lead to varied unwanted effects, depending upon the nature of the grains present in the emulsion and their intended end use.
  • starches that have been heretofore investigated as peptizers have been generally observed to be clearly inferior in their peptizing action.
  • conventional starch peptizers as demonstrated by Maskasky U.S. Patent 5,274,644, cited above, favor the formation of grains having ⁇ 100 ⁇ crystal faces, whereas high bromide tabular grains require ⁇ 111 ⁇ faces in the forms that have found acceptance in practical use.
  • the invention is directed to a radiographic element comprised of a transparent film support and first and second emulsion layer units coated on opposite sides of the support, each including at least one radiation-sensitive emulsion comprised of (a) silver halide grains containing greater than 50 mole percent bromide and less than 4 mole percent iodide, based on silver, with greater than 50 percent of total grain projected area being accounted for by tabular grains having (111) major faces, (b) a spectral sensitizing dye adsorbed to the surfaces of the silver halide grains, and (c) hydrophilic colloid vehicle acting as a peptizer and a binder for the silver halide grains, characterized in that at least the portion of the vehicle acting as a peptizer is a hydrophilic colloid derived from a water dispersible cationic starch.
  • Cationic starches exhibit lower levels of viscosity than have previously been present in preparing tabular grain emulsions, and viscosity is reduced even further when the cationic starch is oxidized. Reduced viscosity facilitates more uniform mixing. Both micromixing, which controls the uniformity of grain composition, mean grain size and dispersity, and bulk mixing, which controls scale up of precipitations to convenient manufacturing scales, are favorably influenced by the reduced viscosities made possible by cationic starch peptizers. Precise control over grain nucleation, including the monodispersity of the grain nuclei, is particularly important to successfully achieving and improving the properties of tabular grain emulsions.
  • Oxidized cationic starch allow emulsion precipitation at ambient temperature. Additionally, oxidized cationic starch allows chemical sensitization at even lower temperatures than cationic starches in general.
  • Figure 1 is a schematic diagram of an assembly consisting of a dual coated radiographic element mounted between two intensifying screens.
  • each emulsion layer unit contains at least one high bromide ⁇ 111 ⁇ tabular grain emulsion.
  • At least one spectral sensitizing dye is adsorbed to the grain surfaces.
  • the optional crossover reducing layer typically contains microcrystalline dye particles to reduce crossover further. To permit transmission viewing of the silver images the microcrystalline dye particles are chosen to be decolorized during processing.
  • these layers employ water permeable hydrophilic colloid vehicles.
  • the sole function of the vehicle is to act as a binder.
  • the vehicle acts both as a binder for coating integrity and as a peptizer for the silver halide grains.
  • a distinguishing feature of the radiographic elements of the invention is that at least that portion of the hydrophilic colloid forming the radiographic element that is used as a peptizer for the high bromide ⁇ 111 ⁇ tabular grain emulsion is derived from a water dispersible cationic starch.
  • starch is employed to include both natural starch and modified derivatives, such as dextrinated, hydrolyzed, oxidized, alkylated, hydroxyalkylated, acetylated or fractionated starch.
  • the starch can be of any origin, such as corn starch, wheat starch, potato starch, tapioca starch, sago starch, rice starch, waxy corn starch or high amylose corn starch.
  • Starches are generally comprised of two structurally distinctive polysaccharides, ⁇ -amylose and amylopectin. Both are comprised of ⁇ -D-glucopyranose units. In ⁇ -amylose the ⁇ -D-glucopyranose units form a 1,4-straight chain polymer.
  • the repeating units take the following form: In amylopectin, in addition to the 1,4-bonding of repeating units, 6-position chain branching (at the site of the -CH 2 OH group above) is also in evidence, resulting in a branched chain polymer.
  • the repeating units of starch and cellulose are diasteroisomers that impart different overall geometries to the molecules.
  • the ⁇ anomer found in starch and shown in formula I above, results in a polymer that is capable of crystallization and some degree of hydrogen bonding between repeating units in adjacent molecules, but not to the same degree as the ⁇ anomer repeating units of cellulose and cellulose derivatives.
  • Polymer molecules formed by the ⁇ anomers show strong hydrogen bonding between adjacent molecules, resulting in clumps of polymer molecules and a much higher propensity for crystallization. Lacking the alignment of substituents that favors strong intermolecular bonding, found in cellulose repeating units, starch and starch derivatives are much more readily dispersed in water.
  • the water dispersible starches employed in the practice of the invention are cationic--that is, they contain an overall net positive charge when dispersed in water.
  • Starches are conventionally rendered cationic by attaching a cationic substituent to the ⁇ -D-glucopyranose units, usually by esterification or etherification at one or more free hydroxyl sites.
  • Reactive cationogenic reagents typically include a primary, secondary or tertiary amino group (which can be subsequently protonated to a cationic form under the intended conditions of use) or a quaternary ammonium, sulfonium or phosphonium group.
  • the cationic starch must be water dispersible. Many starches disperse in water upon heating to temperatures up to boiling for a short time (e.g., 5 to 30 minutes). High sheer mixing also facilitates starch dispersion. The presence of cationic substituents increases the polar character of the starch molecule and facilitates dispersion.
  • the starch molecules preferably achieve at least a colloidal level of dispersion and ideally are dispersed at a molecular level-i.e., dissolved.
  • the starch is oxidized either before (* patents above) or following the addition of cationic substituents. This is accomplished by treating the starch with a strong oxidizing agent.
  • a strong oxidizing agent Both hypochlorite (ClO - ) or periodate (IO 4 - ) have been extensively used and investigated in the preparation of commercial starch derivatives and are preferred. While any convenient counter ion can be employed, preferred counter ions are those fully compatible with silver halide emulsion preparation, such as alkali and alkaline earth cations, most commonly sodium, potassium or calcium.
  • the oxidation sites are at the 2 and 3 position carbon atoms forming the ⁇ -D-glucopyranose ring.
  • the 2 and 3 position groups are commonly referred to as the glycol groups.
  • the carbon-to-carbon bond between the glycol groups is replaced in the following manner: where R represents the atoms completing an aldehyde group or a carboxyl group.
  • hypochlorite oxidation of starch is most extensively employed in commercial use.
  • the hypochlorite is used in small quantities ( ⁇ 0.1 % by weight chlorine, based on total starch) to modify impurities in starch, most notably to bleach colored impurities. Any modification of the starch at these low levels is minimal, at most affecting only the polymer chain terminating aldehyde groups, rather than the ⁇ -D-glucopyranose repeating units themselves.
  • the hypochlorite affects the 2, 3 and 6 positions, forming aldehyde groups at lower levels of oxidation and carboxyl groups at higher levels of oxidation.
  • Oxidation is conducted at mildly acidic or alkaline pH (e.g., >5 to 11). The oxidation reaction is exothermic, requiring cooling of the reaction mixture. Temperatures of less than 45°C are preferably maintained. Using a hypobromite oxidizing agent is known to produce similar results as hypochlorite.
  • hypochlorite oxidation is catalyzed by the presence of bromide ions. Since silver halide emulsions are conventionally precipitated in the presence of a stoichiometric excess of the halide to avoid inadvertent silver ion reduction (fogging), it is conventional practice to have bromide ions in the dispersing media of high bromide silver halide emulsions. Thus, it is specifically contemplated to add bromide ion to the starch prior to performing the oxidation step in the concentrations known to be useful in the precipitation of silver halide emulsions.
  • Cescato U.S. Patent 3,706,584 discloses techniques for the hypochlorite oxidation of cationic starch.
  • Sodium bromite, sodium chlorite and calcium hypochlorite are named as alternatives to sodium hypochlorite.
  • Further teachings of the hypochlorite oxidation of starches is provided by the following: R.L. Whistler, E.G. Linke and S. Kazeniac, "Action of Alkaline Hypochlorite on Corn Starch Amylose and Methyl 4-O-Methyl-D-glucopyranosides", Journal Amer. Chem. Soc., Vol. 78, pp. 4704-9 (1956); R.L. Whistler and R.
  • one or more soluble salts may be released during the oxidation step.
  • the soluble salts correspond to or are similar to those conventionally present during silver halide precipitation
  • the soluble salts need not be separated from the oxidized starch prior to silver halide precipitation. It is, of course, possible to separate soluble salts from the oxidized cationic starch prior to precipitation using any conventional separation technique. For example, removal of halide ion in excess of that desired to be present during grain precipitation can be undertaken. Simply decanting solute and dissolved salts from oxidized cationic starch particles is a simple alternative. Washing under conditions that do not solubilize the oxidized cationic starch is another preferred option.
  • the carboxyl groups formed by oxidation take the form -C(O)OH, but, if desired, the carboxyl groups can, by further treatment, take the form -C(O)OR', where R' represents the atoms forming a salt or ester. Any organic moiety added by esterification preferably contains from 1 to 6 carbon atoms and optimally from 1 to 3 carbon atoms.
  • a preferred objective is to reduce the viscosity of the cationic starch by oxidation to less than four times (400 percent of) the viscosity of water at the starch concentrations employed in silver halide precipitation.
  • this viscosity reduction objective can be achieved with much lower levels of oxidation, starch oxidations of up to 90 percent of the ⁇ -D-glucopyranose repeating units have been reported (Wurzburg, cited above, p. 29).
  • a typical convenient range of oxidation ring-opens from 3 to 50 percent of the ⁇ -D-glucopyranose rings.
  • the water dispersible cationic starch is present during the precipitation (during nucleation and grain growth or during grain growth) of the high bromide (111) tabular grains.
  • precipitation is conducted by substituting the water dispersible cationic starch for all conventional gelatino-peptizers.
  • the concentrations of the selected peptizer and the point or points of addition can correspond to those employed using gelatino-peptizers.
  • the high bromide ⁇ 111 ⁇ tabular grain emulsions can exhibit mean grain ECD's of any conventional value, ranging up to 10 ⁇ m, which is generally accepted as the maximum mean grain size compatible with radiographic imaging.
  • the tabular grain emulsions of the invention typically exhibit a mean ECD in the range of from about 0.5 to 5.0 ⁇ m.
  • tabular grains impart to emulsions generally increases as the average aspect ratio or tabularity of the tabular grain emulsions increases. Both aspect ratio (ECD/t) and tabularity (ECD/t 2 ) increase as average tabular grain thickness decreases. Therefore it is generally sought to minimize the thicknesses of the tabular grains to the extent possible for the intended application. Absent specific application prohibitions, it is generally preferred that the tabular grains have an average aspect ratio of greater than 5 and most preferably greater than 8. Tabular grain average aspect ratios can range up to 100 or higher, but are typically in the range of from about 12 to 80. Tabularities of >25 are generally preferred.
  • silver salts can be epitaxially grown onto the tabular grains during the precipitation process. Epitaxial deposition onto the edges and/or corners of tabular grains is specifically taught by Maskasky U.S. Patent 4,435,501, cited above. In a specifically preferred form high chloride silver halide epitaxy is present at the edges or, most preferably, restricted to corner adjacent sites on the tabular grains.
  • the emulsions of the invention show unexpected sensitivity enhancements with or without epitaxy when chemically sensitized in the absence of gelatin or gelatin derivates, employing one or a combination of noble metal, middle chalcogen and reduction chemical sensitization techniques.
  • Conventional chemical sensitizations by these techniques are summarized in Research Disclosure , Item 36544, cited above, Section IV. Chemical sensitizations. All of these sensitizations, except those that specifically require the presence of gelatin (e.g., active gelatin sensitization) are applicable to the practice of the invention. It is preferred to employ at least one of noble metal (typically gold) and middle chalcogen (typically sulfur) and, most preferably, a combination of both in preparing the emulsions of the invention for photographic use.
  • noble metal typically gold
  • middle chalcogen typically sulfur
  • emulsion washing can be combined with emulsion precipitation, using ultrafiltration during precipitation as taught by Mignot U.S. Patent 4,334,012.
  • emulsion washing by diafiltration after precipitation and before chemical sensitization can be undertaken with a semipermeable membrane as illustrated by Research Disclosure, Vol. 102, October 1972, Item 10208, Hagemaier et al Research Disclosure , Vol.
  • middle chalcogen sensitizers are tetrasubstituted middle chalcogen ureas of the type disclosed by Herz et al U.S. Patents 4,749,646 and 4,810,626.
  • Preferred compounds include those represented by the formula: wherein
  • Preferred 2-[N-(2-alkynyl)amino]- meta -chalcoazoles can be represented by the formula: where
  • the formula V compounds are generally effective (with the Vb form giving very large speed gains and exceptional latent image stability) when present during the heating step (finish) that results in chemical sensitization.
  • Patent 4,439,520 discloses advantages for "dye in the finish" sensitizations, which are those that introduce the spectral sensitizing dye into the emulsion prior to the heating step (finish) that results in chemical sensitization.
  • Maskasky U.S. Patent 4,435,501 teaches the use of aggregating spectral sensitizing dyes, particularly green and red absorbing cyanine dyes, as site directors for epitaxial deposition. These dyes are present in the emulsion prior to the chemical sensitizing finishing step. When the spectral sensitizing dye present in the finish is not relied upon as a site director for the silver salt epitaxy, a much broader range of spectral sensitizing dyes is available.
  • spectral sensitizing dyes disclosed by Kofron et al particularly the blue spectral sensitizing dyes shown by structure and their longer methine chain analogous that exhibit absorption maxima in the green and red portions of the spectrum, are particularly preferred for incorporation in the tabular grain emulsions of the invention.
  • a more general summary of useful spectral sensitizing dyes is provided by Research Disclosure , Item 36544, cited above, Section V. Spectral sensitization and desensitization.
  • starch When starch is employed as a binder, it can be hardened with conventional starch crosslinking agents.
  • One of the most widely employed crosslinking agents for starch is epichlorohydrin.
  • Other known crosslinking agents include ⁇ , ⁇ '-dichlorodiethyl ether; dibasic organic acids reacted under condtions such that both carboxyl groups esterify starch hydroxyl groups; phosphorus oxychloride; trimetaphosphate; mixed anhydrides of acetic and di- or tri-basic carboxylic acids; vinyl sulfone; diepoxides; cyanuric chloride; hexahydro-1,3,5-trisacryloyl-s-triazine; hexamethylene diisocyante; toluene 2,4-diisocyanate; N,N-dimethylenebisacrylamide; N,N'-bis(hydroxymethyl)ethyleneurea; phosgene; tripolyphosphate; mixed carbonic
  • Patent 2,989,521 Commerford et al U.S. Patent 2,977,356; Gerwitz U.S. Patent 2,805,220; Wimmer U.S. Patent 2,910,467; Trimmell et al U.S. Patents 3,035,045 and 3,086,971; Sowell et al U.S. Patent 3,001,985; Smith et al U.S. Patent 3,069,410; Jarowenko et al U.S. Patent 3,376,287; Speakman U.S. Patents 3,549,618 and 3,705,046; Jarowenko U.S. Patent 3,553,195; Tessler et al U.S.
  • the AgNO 3 solution was added at 10 mL per min for 1 min then its addition rate was accelerated to 50 mL per min in 30 min until a total of 1.00 L had been added.
  • the salt solution was concurrently added at a rate needed to maintain a constant pBr of 1.76.
  • the resulting tabular grain emulsion was washed by diafiltration at 40°C to a pBr of 3.38.
  • the tabular grain population of the resulting tabular grain emulsion was comprised of tabular grains with an average equivalent circular diameter of 1.2 ⁇ m, an average thickness of 0.06 ⁇ m, and an average aspect ratio of 20.
  • the tabular grain population made up 92% of the total projected area of the emulsion grains.
  • the emulsion grains had a coefficient of variation in diameter of 18%.
  • This emulsion was prepared similarly to Example 2, except that the starch used was a cationic amphoteric potato starch (Wespol A ®, obtained from Western Polymer Corporation, Moses Lake, WA.) containing both a quaternary trimethyl ammonium alkyl starch ether, 0.36 wt% nitrogen, and orthophosphate (0.70 wt% phosphorus) substituents.
  • a cationic amphoteric potato starch Wespol A ®, obtained from Western Polymer Corporation, Moses Lake, WA.
  • the tabular grain population of the resulting emulsion was comprised of tabular grains with an average equivalent circular diameter of 1.7 ⁇ m, an average thickness of 0.05 ⁇ m, and an average aspect ratio of 34.
  • the tabular grain population made up 95% of the total projected area of the emulsion grains.
  • Example 4 AgIBr (3 mole% I) Tabular Grain Emulsion Made Using a Cationic Amphoteric Potato Starch
  • This emulsion was prepared similarly to Example 3, except that the precipitation was stopped after 50 mL of the AgNO 3 solution was added.
  • Example 5 AgIBr (3 mole% I) Tabular Grain Emulsion Made Using a Cationic Potato Starch and at pH 2.0.
  • This emulsion was prepared similarly to Example 2, except that the emulsion was precipitated at pH 2.0 and the starch used was cationic potato starch (STA-LOK ® 400).
  • This emulsion was prepared similarly to Example 2, except that the emulsion was precipitated at pH 6.0, and the starch used was a cationic waxy corn starch (STA-LOK ®180, obtained from A. E. Staley Manufacturing Co.) made up of 100% amylopectin derivatized to contain 0.36 wt% nitrogen in the form of a quaternary trimethyl ammonium alkyl starch ether and 0.06 wt% phosphorus, average molecular weight 324,000.
  • STA-LOK ®180 cationic waxy corn starch
  • the tabular grain population of the resulting emulsion was comprised of tabular grains with an average equivalent circular diameter of 1.6 ⁇ m, an average thickness of 0.06 ⁇ m, and an average aspect ratio of 27.
  • the tabular grain population made up 91% of the total projected area of the emulsion grains.
  • Example 7 AgBr Tabular Grain Emulsion Made by Adding 94% of a Cationic Potato Starch After Grain Nucleation
  • a starch solution was prepared by boiling for 30 min a stirred 200 g aqueous mixture containing 3.75 mmoles of NaBr and 8.0 g of the cationic potato starch STA-LOK ® 400.
  • the starch solution (7.5 g starch) was added, the pH was adjusted to 6.0 and maintained at this value throughout the remainder of the precipitation, and the AgNO3 solution was added at 1.0 mL per min for 3 min and the NaBr solution was concurrently added at a rate needed to maintain a pBr of 1.76. Then the addition of the NaBr solution was stopped but the addition of the AgNO3 solution was continued at 1.0 mL per min until a pBr of 2.00 was obtained. Then the addition of the AgNO 3 was accelerated at 0.05 mL per min squared and the NaBr solution was added as needed to maintain a pBr of 2.00 until a total of 0.20 mole of silver had been added.
  • the tabular grain population of the resulting emulsion was comprised of tabular grains with an average equivalent circular diameter of 1.6 ⁇ m, an average thickness of 0.07 ⁇ m, and an average aspect ratio of 23.
  • the tabular grain population made up 80% of the total projected area of the emulsion grains.
  • Example 9 AgBr Tabular Grain Emulsion Made Using a Cationic Potato Starch
  • the AgNO3 solution was added at 1.0 mL per min for 1 min then its addition rate was accelerated to 5 mL per min in 30 min then held at this rate until a total of 200 mL of the AgNO 3 solution had been added.
  • the salt solution was concurrently added at a rate needed to maintain a constant pBr of 1.76.
  • Example 10 AgIBr (3 mole% I) Tabular Grain Emulsion Made Using a Protonated Tertiary Aminoalkyl (Cationic) Corn Starch
  • This emulsion was prepared similarly to Example 2, except that the starch used was a corn starch (CATO-SIZE ® 69, obtained from National Starch and Chemical Co.) that, as obtained, was derivatized to contain tertiary aminoalkyl starch ethers, 0.25 wt% nitrogen, 0.06 wt% phosphorus. At a pH of 5.5, the tertiary amino groups were protonated to render the starch cationic.
  • the tabular grain population of the resulting emulsion was comprised of tabular grains with an average equivalent circular diameter of 1.2 ⁇ m, an average thickness of 0.08 ⁇ m, and an average aspect ratio of 15.
  • the tabular grain population made up 55% of the total projected area of the emulsion grains.
  • Example 11 AgIBr (3 mole% I) Tabular Grain Emulsion Made Using a Cationic Potato Starch and at pH 5.5 and 80°C.
  • the tabular grain population of the emulsion was comprised of tabular grains with an average equivalent circular diameter of 1.7 ⁇ m, an average thickness of 0.07 ⁇ m, and an average aspect ratio of 24.
  • the tabular grain population made up 80% of the total projected area of the emulsion grains.
  • Example 12 AgIBr (3 mole% I) Tabular Grain Emulsion Made Using a Cationic Corn Starch
  • This emulsion was prepared similarly to Example 2, except that the starch used was a cationic corn starch (CATO ® 25, obtained from National Starch and Chemical Company) containing 0.26 wt% nitrogen and 0.00 wt% phosphorus.
  • CAO ® 25 obtained from National Starch and Chemical Company
  • the tabular grain population of the resulting emulsion was comprised of tabular grains with an average equivalent circular diameter of 1.2 ⁇ m, an average thickness of 0.07 ⁇ m, and an average aspect ratio of 17.
  • the tabular grain population made up 65% of the total projected area of the emulsion grains.
  • This emulsion was prepared similarly to Example 2, except that the starch used was a cationic corn starch (Clinton 788 ®, obtained from ADM Corn Processing, Clinton, IA) containing 0.15 wt% nitrogen and 0.00 wt% phosphorus.
  • a cationic corn starch (Clinton 788 ®, obtained from ADM Corn Processing, Clinton, IA) containing 0.15 wt% nitrogen and 0.00 wt% phosphorus.
  • the tabular grain population of the resulting emulsion was comprised of tabular grains with an average equivalent circular diameter of 1.0 ⁇ m, an average thickness of 0.08 ⁇ m, and an average aspect ratio of 13.
  • the tabular grain population made up 60% of the total projected area of the emulsion grains.
  • Example 14 AgIBr (3 mole% I) Tabular Grain Emulsion Made Using a Cationic Wheat Starch
  • This emulsion was prepared similarly to Example 2, except that the starch used was a cationic wheat starch (K-MEGA® 53S, obtained from ADM/Ogilvie, Montreal, Quebec, Canada), which, as received was derivatized with a quaternary amine. The degree of substitution is 0.050 corresponding to 0.41 wt% nitrogen. The phosphorus was determined spectrophotometrically to be 0.07 wt%.
  • K-MEGA® 53S cationic wheat starch
  • the tabular grain population of the resulting emulsion was comprised of tabular grains with an average equivalent circular diameter of 1.5 ⁇ m, an average thickness of 0.08 ⁇ m, and an average aspect ratio of 19.
  • the tabular grain population made up 85% of the total projected area of the emulsion grains.
  • Example 15 AgBr Tabular Grain Emulsion Made Using a Cationic Potato Starch
  • a starch solution was prepared by boiling for 30 min a stirred 400 g aqueous mixture containing 2.7 mmoles of NaBr and 8.0 g of the cationic potato starch STA-LOK ® 400.
  • the resulting solution was cooled to 35°C, readjusted to 400 g with distilled water.
  • pH 6.0 pH 6.0 was added 2 M AgNO 3 solution at a constant rate of 10 mL per min.
  • a 2 M NaBr solution was added initially at 10 mL per min and then at a rate needed to maintain a pBr of 2.21.
  • the addition of the solutions was stopped, 2.5 mL of 2M NaBr was added rapidly, and the temperature of the contents of the reaction vessel was increased to 50°C at a rate of 5°C per 3 min.
  • the pH was adjusted to 6.0 and the AgNO3 solution was added at 1.0 mL per min for 1 min, then its addition rate was accelerated to reach a flow rate of 5 mL per min in 30 min and held at this rate until a total of 200 mL of the AgNO 3 solution had been added.
  • the salt solution was concurrently added at a rate needed to maintain a constant pBr of 1.76.
  • the tabular grain population of the resulting emulsion was comprised of tabular grains with an average equivalent circular diameter of 1.2 ⁇ m, an average thickness of 0.10 ⁇ m, and an average aspect ratio of 12.
  • the tabular grain population made up 70% of the total projected area of the emulsion grains.
  • Example 16 AgIBr (3 mole% I) Tabular Grain Emulsion Made Using a Cationic Potato Starch of High Nitrogen Content
  • a cationic potato starch solution containing a high nitrogen content was supplied by Western Polymer Corporation.
  • the starch was 1.10 wt% in nitrogen and 0.25 wt% in natural phosphorus.
  • the tabular grain population of the resulting emulsion was comprised of tabular grains with an average equivalent circular diameter of 1.2 ⁇ m, an average thickness of 0.09 ⁇ m, and an average aspect ratio of 13.
  • the tabular grain population made up 80% of the total projected area of the emulsion grains.
  • Example 17 AgBr Tabular Grain Emulsion Made Using a Cationic Potato Starch
  • a starch solution was prepared by boiling for 30 min a stirred 400 g aqueous mixture containing 2.7 mmoles of NaBr and 8.0 g of the cationic potato starch STA-LOK ® 400.
  • the resulting solution was cooled to 35°C, readjusted to 400 g with distilled water.
  • pH 6.0 pH 6.0 was added 2 M AgNO 3 solution at a constant rate of 10 mL per min.
  • a salt solution of 2.5 M NaBr was added initially at 10 mL per min and then at a rate needed to maintain a pBr of 2.21.
  • the addition of the solutions was stopped, 2.5 mL of 2M NaBr was added rapidly, and the temperature of the contents of the reaction vessel was increased to 60°C at a rate of 5°C per 3 min.
  • the tabular grain population of the resulting emulsion was comprised of tabular grains with an average equivalent circular diameter of 2..0 ⁇ m, an average thickness of 0.14 ⁇ m, and an average aspect ratio of 14.
  • the tabular grain population made up 85% of the total projected area of the emulsion grains.
  • This emulsion was prepared similarly to Example 2, except that the starch used was a corn starch (FILMKOTE ® 54, obtained from National Starch and Chemical Co.), which, as supplied, was derivatized to contain carboxylate groups. The nitrogen content was natural, 0.06 wt%.
  • This emulsion was prepared similarly to Example 2, except that the starch used was an orthophosphate derivatized potato starch 0.03 wt% nitrogen (natural), and orthophosphate substituents, 0.66 wt% phosphorus.
  • the sample was obtained from Western Polymer Corporation.
  • This emulsion was prepared similarly to Example 2, except that the starch (Soluble Potato Starch obtained from Sigma Chemical Company, St. Louis, MO.) used was a treated and purified water soluble potato starch, 0.04 wt% nitrogen and 0.06 wt% phosphorus.
  • starch Soluble Potato Starch obtained from Sigma Chemical Company, St. Louis, MO.
  • This example demonstrates to the failure of the grain protein zein to act as a peptizer.
  • This emulsion was prepared similarly to Example 2, except that the polysaccharide dextran (obtained from Sigma Chemical Co., St. Louis, MO.), having a molecular weight of approximately 500,000, was employed.
  • polysaccharide dextran obtained from Sigma Chemical Co., St. Louis, MO.
  • This emulsion was prepared similarly to Example 2 except that the polysaccharide used was agar (purified, ash content ⁇ 2%), obtained from Sigma Chemical Co.
  • Agar was a poor peptizer for silver halide grains.
  • This emulsion was prepared similarly to Example 2, except that the polysaccharide used was pectin from citrus fruit (obtained from Sigma Chemical Co).
  • This emulsion was prepared similarly to Example 2, except that oxidized bone gelatin was substituted for the starch.
  • This emulsion was prepared similarly to Control Example 28, except that precipitation was terminated after the addition of 0.1 mole of silver nitrate.
  • the tabular grain population of the resulting emulsion was comprised of tabular grains with an average equivalent circular diameter of 2.0 ⁇ m, an average thickness of 0.06 ⁇ m, and an average aspect ratio of 33.
  • the tabular grain population made up only 30% of the total projected area of the emulsion grains.
  • This emulsion was prepared similarly to Example 2, except that oxidized bone gelatin was substituted for the starch and the precipitation growth temperature was 60°C, instead of 50°C.
  • the emulsion was diafiltered-washed to a pBr of 3.38 at 40°C.
  • the tabular grains had an average equivalent circular diameter of 2.45 ⁇ m, an average thickness of 0.06 ⁇ m, and an average aspect ratio of 41.
  • the tabular grain population made up 95% of the total projected area of the emulsion grains.
  • Example 1 STA The tabular grain emulsion of Example 1, precipitated in the presence of cationic starch, was divided into three portions to form three samples. Two portions received no further treatment until sensitization, "Example 1 STA” and “Example 1 STA-Spectral”. The samples were identical, but the latter sample received only spectral sensitization, instead of chemical and spectral sensitization, as in the case of the remaining emulsion samples.
  • Example 1 GEL 20 g of bone gelatin in 100 mL distilled water were added.
  • the purpose of adding gelatin was to demonstrate the effect of gelatin added as a vehicle after precipitation and before chemical sensitization, as is conventional practice.
  • a fourth emulsion sample was taken from a conventional silver iodobromide (2.7 mole % I) tabular grain precipitated in bone gelatin, Control Example 31.
  • the purpose of providing this sample was to compare the properties of an emulsion precipitated in gelatin to the emulsions precipitated in the absence of gelatin and sensitized either in the presence or absence of gelatin.
  • the resulting sensitized emulsions were mixed with gelatin, yellow dye-forming coupler dispersion, surfactants, and hardener and coated onto clear support at 0.84 g/m 2 silver, 1.7 g/m 2 yellow dye-forming coupler, and 3.5 g/m 2 bone gelatin.
  • the coatings were exposed to blue light for 0.02 sec through a 0 to 4.0 log density graduated step tablet, processed in the Kodak Flexicolor C-41 color negative process using a development time of 3 min 15 sec.
  • Example 1 GEL which was precipitated in cationic starch, but had gelatin added before chemical sensitization, exhibited a speed that was 15 relative speed units faster than the speed of Control Example 31.
  • Example 1 STA Quite surprising was the large speed advantage demonstrated by Example 1 STA.
  • This emulsion which precipitated and sensitized in the absence of gelatin, was 1.04 log E faster than Control Example 31. In other words, it was more than 10 times faster than the conventional Control Example 31 emulsion.
  • Example 1 STA prepared as described in Example 32 was treated with a 0.2 wt% solution of active proteolytic enzyme (H.T.-Proteolytic 200 from Miles Labs, Inc., Elkhart, IN) for 30 min at 35°C to degrade the gelatin.
  • active proteolytic enzyme H.T.-Proteolytic 200 from Miles Labs, Inc., Elkhart, IN
  • the emulsion grains were washed twice in distilled water and examined by infra-red spectroscopy. The infra-red absorption spectrum of the starch was clearly observed, demonstrating that the starch remained a permanent part of the emulsion and was not removed by washing.
  • a 2 percent by weight cationic starch solution, CS was prepared by boiling for 30 min a stirred mixture of 8 g STA-LOK® 400, 2.7 mmoles of NaBr and distilled water to 400 mL. The solution was sonicated for 3 min. The resulting solution was cooled to 40°C, readjusted to 400 mL with distilled water, sonicated for 3 min, and the pH adjusted to 6.0.
  • GEL gealtin solution
  • the viscosity data show that cationic starch has low viscosity at low temperatures while the gelatin solution solidified. This makes cationic starch particularly useful for silver halide grain nucleation and/or growth at temperatures below 25°C.
  • OCS-1 An oxidized cationic starch solution (OCS-1) was prepared by boiling for 30 min a stirred mixture of 80 g cationic potato starch, 27 mmoles of NaBr and distilled water to 4 L.
  • the starch, STA-LOK ® 400 was obtained from A. E. Staley Manufacturing Co., Decatur, IL., and is a mixture of 21% amylose and 79% amylopectin, 0.33 wgt % nitrogen in the form of a quaternary trimethyl ammonium alkyl starch ether, 0.13 wgt % natural phosphorus, average molecular weight 2.2 million.
  • GEL-1 gelation
  • the viscosity data show that the oxidized cationic starch has the lowest viscosity at low temperatures (less than about 25°C). This low viscosity makes it desirable for silver halide grain nucleation and/or growth at temperatures below 25°C.
  • the AgNO 3 solution was added at 10 mL per min for 1 min then its addition rate was accelerated to 40 mL per min in 30 min and held at this flow rate until a total of 2 moles of silver had been added.
  • the iodide containing salt solution was concurrently added at a rate needed to maintain a constant pBr of 1.76.
  • the resulting tabular grain emulsion was washed by diafiltration at 40°C to a pBr of 3.38.
  • the tabular grains had an average equivalent circular diameter (ECD) of 1.1 ⁇ m, an average thickness of 0.05 ⁇ m, and an average aspect ratio of 22.
  • ECD average equivalent circular diameter
  • the tabular grain population made up 95% of the total projected area of the emulsion grains.
  • the emulsion grains had a coefficient of variation in diameter of 21%.
  • Example 36 AgIBr (3 mole% I) Ultrathin Tabular Grain Emulsion Made Using Oxidized Cationic Starch an a Growth pBr of 2.0
  • the AgNO 3 solution was added at 1.0 mL per min and the salt solution was added at a rate needed to maintain a pBr of 1.76. After 3 min of precipitation at this pBr, the flow of the salt solution was stopped until a pBr of 2.00 was reached. The AgNO 3 solution flow rate was then accelerated at a rate that would have reached 4 mL per min in 60 min until a total of 0.20 mole of silver had been added. The iodide containing salt solution was added as needed to maintain a pBr of 2.00.
  • the tabular grain population of the resulting emulsion was comprised of ultrathin tabular grains with an average equivalent circular diameter of 1.7 ⁇ m, an average thickness of 0.055 ⁇ m, and an average aspect ratio of 31.
  • the tabular grain population made up 95% of the total projected area of the emulsion grains.
  • This emulsion was prepared similarly to Example 36, except that the precipitation was stopped after a total of 0.10 mole of the AgNO 3 solution was added.
  • the tabular grain population of the resulting emulsion was comprised of ultra-thin tabular grains with an average equivalent circular diameter of 1.2 ⁇ m, an average thickness of 0.040 ⁇ m, and an average aspect ratio of 30.
  • the tabular grain population made up 95% of the total projected area of the emulsion grains.
  • Example 38 AgIBr (3 mole% I) Ultrathin Tabular Grain Emulsion Made Using Oxidized Cationic Starch and a Growth pBr of 1.5
  • the AgNO3 solution was added at 1.0 mL per min and the salt solution was added at a rate needed to maintain a pBr of 1.76. After 3 min of precipitation at this pBr, the flow of the silver and salt solutions was stopped and 2.75 mL of a 2.0 M NaBr solution was added. The AgNO3 solution flow rate was then accelerated at a rate that would have reached 4 mL per min in 60 min until a total of 0.20 mole of silver had been added. The iodide containing salt solution was added as needed to maintain a pBr of 1.5.
  • This emulsion was prepared similarly to Example 38, except that the precipitation was stopped after a total of 0.10 mole of the AgNO 3 solution was added.
  • Example 40 AgIBr (3 mole% I) Ultrathin Tabular Grain Emulsion Made Using Oxidized Cationic Starch and Low Temperature Grain Nucleation
  • the AgNO3 solution was added at 1.0 mL per min and the salt solution was added at a rate needed to maintain a pBr of 1.76. After 3 min of precipitation at this pBr, the AgNO 3 solution flow rate was accelerated to 4 mL per min in 60 min and held at this rate until a total of 0.40 mole of silver had been added. The iodide containing salt solution was added as needed to maintain a pBr of 1.76.
  • the tabular grain population of the resulting ultrathin tabular grain emulsion was comprised of ultra-thin tabular grains with an average equivalent circular diameter of 1.8 ⁇ m, an average thickness of 0.06 ⁇ m, and an average aspect ratio of 30.
  • the tabular grain population made up 95% of the total projected area of the emulsion grains.
  • This emulsion was prepared similarly to Example 40, except that the precipitation was stopped after a total of 0.20 mole of silver was added.
  • the tabular grain population of the resulting emulsion was comprised of ultrathin tabular grains with an average equivalent circular diameter of 1.3 ⁇ m, an average thickness of 0.045 ⁇ m, and an average aspect ratio of 29.
  • the tabular grain population made up 98% of the total projected area of the emulsion grains.
  • This emulsion was prepared similarly to Example 40, except that the precipitation was stopped after a total of 0.10 mole of the AgNO3 solution was added.
  • the tabular grain population of the resulting emulsion was comprised of ultra-thin tabular grains with an average equivalent circular diameter of 1.0 ⁇ m, an average thickness of 0.040 ⁇ m, and an average aspect ratio of 25.
  • the tabular grain population made up 98% of the total projected area of the emulsion grains.
  • This emulsion was prepared similarly to Example 40, except that the precipitation was stopped after a total of 0.05 mole of the AgNO3 solution was added.
  • the average thickness was determined by scanning 195 tabular grains using atomic force microscopy to obtain an average tabular grain plus adsorbed starch thickness.
  • the measured starch thickness of 0.0030 ⁇ m (the sum of both sides) was subtracted from this value.
  • the corrected average thickness was 0.034 ⁇ m.
  • the area weighted equivalent circular diameter was 0.70 ⁇ m.
  • the average aspect ratio was 21.
  • the tabular grain population made up 98% of the total projected area of the emulsion grains.
  • This emulsion was prepared similarly to Example 38, except that the starch used was soluble potato starch obtained from Sigma Chemical Company, St. Louis, MO. The starch was oxidized using the same procedure used for the starch of Example 38.
  • the purpose of this example is to demonstrate the effect on photographic performance of varied peptizers and peptizer combinations.
  • Emulsions were prepared with five different selections of peptizers introduced before chemical sensitization.
  • Control Example 31 emulsion was employed.
  • Gelatin was the sole peptizer present prior to chemical sensitization.
  • Example 1 The Example 1 emulsion was employed. As precipitated nonoxidized cationic starch (CS) was present. Before chemical sensitization an additional 25 g of bone gelatin per mole of silver was added.
  • CS precipitated nonoxidized cationic starch
  • Example 1 The Example 1 emulsion was employed. Only nonoxidized cationic starch (CS) was present before chemical sensitization.
  • CS nonoxidized cationic starch
  • Example 35 emulsion prepared using oxidized cationic starch as the peptizer was modified by the addition of 25 g of bone gelatin per mole of silver before chemical sensitization.
  • Example 35 The Example 35 emulsion was employed. Only oxidized cationic starch (OCS) was present before chemical sensitization.
  • OCS oxidized cationic starch
  • the coatings were exposed to blue light for 0.02 sec through a 0 to 4.0 log density graduated step tablet, processed in the Kodak Flexicolor C-41 a color negative process using a development time of 3 min 15 sec.
  • Table IV shows that, after sensitization, the photographic speed of OCS ONLY, sensitized at relatively low temperatures (45°C and 50°C) and without the 2-propargylaminobenzoxazole (R) was far superior to the other emulsions sensitized at similarly low temperatures, even when the propargyl compound (R) was added to boost speed.
  • the presence of gelatin significantly retarded the ability of GEL ONLY, CS + GEL, and OCS + GEL to be effectively sensitized. Only by using higher temperatures for their chemical sensitization did these control emulsions approach the photographic speed of OCS ONLY sensitized at 45°C and 50°C.
  • OCS ONLY sensitized at 45°C with S + Au was 1.8 Log E faster than CS ONLY, similarly sensitized. This demonstrates the lower sensitization temperatures that can be employed using an oxidized cationic starch as the sole peptizer.
  • Table V shows the result of sensitizing OCS ONLY at temperatures of 45, 50, and 55°C and OCS + GEL at a temperature of 65°C.
  • the temperature of 65°C was chosen for OCS + GEL, since this was the lowest chemical sensitization temperature observed to produce a sensitivity level comparable to that OCS ONLY.
  • the resulting average thickness of the tabular grains was no longer ⁇ 0.07 ⁇ m--i.e., no longer ultrathin. Hence the thickness advantage of ultrathin tabular grain emulsions was lost.
  • Example 1 To 0.035 mole of the emulsion of Example 1 at 40°C, with stirring, were added sequentially the following solutions containing (mmole/mole Ag); 2.5 of NaSCN, 0.22 of a benzothiazolium salt, 1.5 of anhydro-5,5'-dichloro-3,3'-bis(3-sulfopropyl)thiacyanine hydroxide, triethylammonium salt, and 0.08 of 1-(3-acetamidophenyl)-5-mercaptotetrazole, sodium salt. The pH was adjusted to 5.9.
  • the anionic starch FILMKOTE ® 54 obtained from National Starch and Chemical Co., Bridgewater, NJ., is a corn starch consisting of approximately 25% amylose and 75% amylopectin and treated with octenylsuccinic anhydride.
  • Emulsion A(SXR) a solution containing 0.16 g of bis(vinylsulfonyl)methane hardener, surfactant, and distilled water to 42 g, were added.
  • the mixture was hand coated on gelatin-subbed cellulose acetate film support to give an expected coverage of 1.5 g/m 2 silver and 4.3 g/m 2 starch. No gelatin was present in the emulsion layer.
  • Emulsion A(SXR) Emulsion A(SXR)
  • SXR Emulsion A(SXR)
  • surfactant a solution containing 0.036 g of bis(vinylsulfonyl)methane hardener, surfactant, and distilled water.
  • the mixture was handcoated on a cellulose acetate film support to give an expected coverage of 1.5 g/m 2 silver and 4.3 g/m 2 of gelatin.
  • Coating AI and Coating AII were exposed to white light for 0.02 sec through a 0 to 4.0 density graduated step-tablet.
  • the exposed films were processed using a commercial Kodak RP X-Omat a rapid processor as follows: development 20 sec at 40°C, fixing 12 sec at 40°C, washing 8 sec at 40°C and drying 20 sec at 65°C.
  • Coating AI had a Dmax of 1.08, Dmin of 0.37, relative speed (at 0.2 above Dmin) of 89 and a mid-scale contrast of 0.51.
  • Coating AII had a Dmax of 1.81, Dmin of 0.68, relative speed (at 0.2 above Dmin) of 100 and a mid-scale contrast of 0.52.
  • the tone of the silver images obtained upon exposure and processing of the radiographic elements were evaluated using the following procedure:
  • the visible transmitted light absorption spectrum was recorded through silver image regions of uniform optical density using a Hitachi Model U-3410 spectrophotometer (commerciall available from Hitachi Instruments, Danbury, Conn.)
  • the color for each region was then denfined by calculation of the CIE (Commission International de l'Eclairage or International Commission on Illumination) tristiulus values, which combines the energy spectrum of the sample with a given illuminant and the CIE standard color functions.
  • the standard illuminant used was the CIE illuminant D 65 representing average daylight.
  • CIE LAB values of b* were obtained by mathematical transforms.
  • the b* values indicate the yellow-blue balance and are a good indicator of warm or cold image tone.
  • a change of approximately 0.7 in the b* value is generally accepted as the just noticeable difference in color which can be detected by observation with the unaided human eye.
  • Increasingly positive values of b* correspond to increasing warmth (yellow hues) of the image.
  • a shift toward negative values and increasingly negative values of b* indicate a shift toward or a cold (blue hue) silver images.
  • Optical photomicrographs at 1500X of a low density portion of the image showed that the developed silver of Coating AI was rod to filamentary in shape while the developed silver of Coating AII was spherical to pseudomorphic. This difference in morphology is believed to have resulted in the observed difference in image tone.
  • the coating used in this example was prepared similarly to that of Coating AI, except that the emulsion-starch-hardener mixture was handcoated on both sides of a gelatin-subbed Estar® poly(ethylene terephthalate) film support to give an expected coverage of 3.0 g/m 2 silver and 8.6 g/m 2 starch. No gelatin was present in the emulsion layer.
  • the resulting dual coated radiographic film was exposed and processed as in Example 48.
  • the resulting tone value b* measured at a density of 1.0 was 2.44.
  • Emulsion B AgBr Tabular Grain Emulsion Made Using a Cationic Potato Starch
  • a cationic starch solution was prepared by boiling for 30 min a stirred mixture of 40 g STA-LOK® 400, 27 mmoles of NaBr, and distilled water to 4L. The resulting solution was cooled to 35°C, readjusted to 4L with distilled water, and the pH was adjusted to 6.0.
  • the AgNO 3 solution was added at 10 mL per min and the 2.5 M NaBr solution was added at a rate needed to maintain a pBr of 1.76. After 3 min of precipitation at this pBr, the flow of the 2.5 M NaBr solution was stopped until a pBr of 2.00 was reached. The addition of the AgNO 3 solution was stopped and a solution consisting of 40 g STA-LOK® 400, 10 mmoles of NaBr, and distilled water to 1 L that was boiled for 30 min and at 60°C was added to the reaction vessel.
  • the AgNO 3 solution flow rate was resumed at 10 mL per min and accelerated to 40 mL per min in 60 min and held at this rate until a total of 2L of AgNO 3 solution was added.
  • the NaBr solution was added as needed to maintain a pBr of 2.00. Then only the AgNO3 solution was added at 10 mL per min until the pBr reached 3.04 then the NaBr solution was concurrently added to maintain this pBr for 20 min. A total of 4.53 moles of silver was added.
  • the resulting tabular grain emulsion was washed by diafiltration at 40°C.
  • the tabular grains had an average equivalent circular diameter of 1.3 ⁇ m, an average thickness of 0.08 ⁇ m, and an average aspect ratio of 16.
  • the tabular grain population made up 95% of the total projected area of the emulsion grains.
  • Emulsion B was chemically and spectrally sensitized to green light.
  • the sensitization used potassium tetrachloroaurate, sodium thiocyanate, sodium thiosulfate, potassium selenocyanate, 350 mg/Ag mole potassium iodide and anhydro-5,5'-dichloro-9-ethyl-3,3'-di-(3-sulfopropyl)oxacarbocyanine hydroxide, triethylamine salt.
  • This coating was made similarly to that of Coating AI, except that Emulsion B(SX) was used. No gelatin was present in the emulsion layer.
  • This coating was made similarly to that of Coating AII, except that Emulsion B(SX) was used.
EP96202226A 1995-08-10 1996-08-07 Zweiseitigbeschichtete radiographische Elemente enthaltend Emulsionen mit tafelförmigen Körnen, die verbesserte Bindemittel enthalten Expired - Lifetime EP0758760B1 (de)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0831361A2 (de) * 1996-09-18 1998-03-25 EASTMAN KODAK COMPANY (a New Jersey corporation) Photographische Elemente mit verbesserten Bindemitteln
EP0833195A1 (de) * 1996-09-30 1998-04-01 Eastman Kodak Company Emulsionen mit ultradünnen Tafelkörnern enthaltende radiographische Elemente
EP1045283A1 (de) * 1999-04-16 2000-10-18 Agfa-Gevaert N.V. Strahlungsempfindliche Emulsion, lichtempfindlicher photographischer Silberhalogenidfilm und Kombination eines radiographischen Verstärkungsschirms mit einem Film
US6200743B1 (en) 1999-04-16 2001-03-13 Agfa-Gevaert, N.V. Radiation-sensitive emulsion, light-sensitive silver halide photographic film material and radiographic intensifying screen-film combination
EP1213608A1 (de) * 2000-12-07 2002-06-12 Eastman Kodak Company Herstellung von photographischen Hochbromidemulsionen, die Stärke als Peptisierer verwendet

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4425425A (en) * 1981-11-12 1984-01-10 Eastman Kodak Company Radiographic elements exhibiting reduced crossover
US5284744A (en) * 1992-08-27 1994-02-08 Eastman Kodak Company Non-ultraviolet-absorbing peptizer for silver halide emulsions

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4425425A (en) * 1981-11-12 1984-01-10 Eastman Kodak Company Radiographic elements exhibiting reduced crossover
US5284744A (en) * 1992-08-27 1994-02-08 Eastman Kodak Company Non-ultraviolet-absorbing peptizer for silver halide emulsions

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0831361A2 (de) * 1996-09-18 1998-03-25 EASTMAN KODAK COMPANY (a New Jersey corporation) Photographische Elemente mit verbesserten Bindemitteln
EP0831361A3 (de) * 1996-09-18 1998-05-13 EASTMAN KODAK COMPANY (a New Jersey corporation) Photographische Elemente mit verbesserten Bindemitteln
EP0833195A1 (de) * 1996-09-30 1998-04-01 Eastman Kodak Company Emulsionen mit ultradünnen Tafelkörnern enthaltende radiographische Elemente
EP1045283A1 (de) * 1999-04-16 2000-10-18 Agfa-Gevaert N.V. Strahlungsempfindliche Emulsion, lichtempfindlicher photographischer Silberhalogenidfilm und Kombination eines radiographischen Verstärkungsschirms mit einem Film
US6200743B1 (en) 1999-04-16 2001-03-13 Agfa-Gevaert, N.V. Radiation-sensitive emulsion, light-sensitive silver halide photographic film material and radiographic intensifying screen-film combination
EP1213608A1 (de) * 2000-12-07 2002-06-12 Eastman Kodak Company Herstellung von photographischen Hochbromidemulsionen, die Stärke als Peptisierer verwendet

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DE69601334T2 (de) 1999-07-15
JPH09120109A (ja) 1997-05-06
DE69601334D1 (de) 1999-02-25
EP0758760B1 (de) 1999-01-13

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