US3155519A - Photographic compositions, layers and elements - Google Patents

Photographic compositions, layers and elements Download PDF

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Publication number
US3155519A
US3155519A US317824A US31782463A US3155519A US 3155519 A US3155519 A US 3155519A US 317824 A US317824 A US 317824A US 31782463 A US31782463 A US 31782463A US 3155519 A US3155519 A US 3155519A
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United States
Prior art keywords
silver
silver halide
emulsion
gelatin
solution
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US317824A
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Blake Ralph Kingsley
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EIDP Inc
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EI Du Pont de Nemours and Co
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Priority to FR88737D priority Critical patent/FR88737E/fr
Priority to NL134365D priority patent/NL134365C/xx
Priority to FR89467D priority patent/FR89467E/fr
Priority to US236417A priority patent/US3155515A/en
Priority to US236418A priority patent/US3155516A/en
Priority to US236420A priority patent/US3155507A/en
Priority to US236412A priority patent/US3155514A/en
Priority to DEP30723A priority patent/DE1226877B/en
Priority to GB46345/62A priority patent/GB1031903A/en
Priority to GB46344/62A priority patent/GB1031902A/en
Priority to DEP30721A priority patent/DE1261397B/en
Application filed by EI Du Pont de Nemours and Co filed Critical EI Du Pont de Nemours and Co
Priority to US317824A priority patent/US3155519A/en
Priority claimed from NL6408533A external-priority patent/NL6408533A/xx
Priority to NL6408533A priority patent/NL6408533A/xx
Priority to DK395464A priority patent/DK119392B/en
Priority to US388919A priority patent/US3418124A/en
Priority to BE651688A priority patent/BE651688A/fr
Priority to US390460A priority patent/US3384485A/en
Priority to CH1270464A priority patent/CH486719A/en
Priority to US403661A priority patent/US3284206A/en
Publication of US3155519A publication Critical patent/US3155519A/en
Application granted granted Critical
Priority to DEP37430A priority patent/DE1294186B/en
Priority to BE668111D priority patent/BE668111A/xx
Priority to GB34231/65A priority patent/GB1111226A/en
Priority to DEP37479A priority patent/DE1293581B/en
Priority to BE670823D priority patent/BE670823A/xx
Priority to GB43289/65A priority patent/GB1124772A/en
Priority to DEP37856A priority patent/DE1293582B/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D263/00—Heterocyclic compounds containing 1,3-oxazole or hydrogenated 1,3-oxazole rings
    • C07D263/52—Heterocyclic compounds containing 1,3-oxazole or hydrogenated 1,3-oxazole rings condensed with carbocyclic rings or ring systems
    • C07D263/54—Benzoxazoles; Hydrogenated benzoxazoles
    • C07D263/58—Benzoxazoles; Hydrogenated benzoxazoles with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached in position 2
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C391/00—Compounds containing selenium
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D277/00—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings
    • C07D277/02—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings not condensed with other rings
    • C07D277/20—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members
    • C07D277/32—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D277/00—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings
    • C07D277/60—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings condensed with carbocyclic rings or ring systems
    • C07D277/62—Benzothiazoles
    • C07D277/68—Benzothiazoles with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached in position 2
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D293/00—Heterocyclic compounds containing rings having nitrogen and selenium or nitrogen and tellurium, with or without oxygen or sulfur atoms, as the ring hetero atoms
    • C07D293/10—Heterocyclic compounds containing rings having nitrogen and selenium or nitrogen and tellurium, with or without oxygen or sulfur atoms, as the ring hetero atoms condensed with carbocyclic rings or ring systems
    • C07D293/12—Selenazoles; Hydrogenated selenazoles
    • 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
    • G03C1/492—Photosoluble emulsions

Definitions

  • An object of this invention is to provide new and useful photographic silver halide layers and elements. Another object is to provide such layers which can be used to form direct positives. Yet another object is to provide such layers and elements which cannot be readily fixed during normal processing periods prior to exposure. A further object is to provide such layers which are easy to make, embody relatively inexpensive chemicals and are dependable in use. Still additional objects will be apparent from the following description of the invention.
  • R is an unsubstituted hydrocarbon radical of 6l0 carbon atoms and has a cyclic hydrocarbon radical of six carbon atoms attached through a cyclic carbon of said radical to the 4-carbon atom of the thiazole ring.
  • Suitable radicals of the latter type include cyclohexyl, methylcyclohexyl, phenyl, tolyl and alpha-naphthyl.
  • the protective silver mercaptide and its concentration relative to the surface area of the silver halide is characterized in that when tested in a gelatino-silver chloro-bromide emulsion (70% silver chloride and 30% silver bromide) which is (a) Applied to a photographic film base at a coating weight of 100 mg./dm. of silver halide and 100 mg./dm. of gelatin,
  • Na2SgO3 (anhyd.) g 100 Na SO (anhyd.) g 9.8 Borax (Na B O -10H O) g 11.8 Acetic acid (glacial) ml 7.8 Potassium alum, KAl(SO '12H O g 13.1 Potassium acetate g 10 1-1 0 to make 900 ml. Adjust pH to 4.8:01 with 3 N H or 3 N NaOH. H O to make 1 liter.
  • At least 25 mg./dm. of silver halide remains in the unexposed areas while no more than 1 mg./dm. of silver halide remains in the area having been given said exposure.
  • the silver mercaptide which is less soluble in water than silver chloride, is further characterized in that when such silver mercaptide is formed by addition of an organic mercaptan or ion thereof to an aqueous dispersion of silver halide, said silver mercaptide protects the silver halide from solution to the extent that at least three times the amount of silver halide remains undissolved as compared to (a) the untreated silver halide dispersion or (b) the mercaptan-treated silver halide dispersion which has subsequently been treated with 5% aqueous sodium hypochlorite, when all three of said dispersions are treated individually with equal amounts of 10% aqueous sodium thiosulfate and agitated identically for 30 seconds at 25 C.
  • the silver halide crystals are dispersed in a water-permeable organic colloid to form a light-sensitive photographic silver halide emulsion.
  • the 4-hydrocarbon substituted-Z-mercaptometathiazole can be added to the silver halide emulsion while the latter is in the liquid state or the emulsion may be coated on a suitable support and the resulting element bathed or impregnated with a solution, e.g., an alcoholic solution of the organic compound.
  • the amount of organic compound in the silver halide emulsion is from about 0.4 to 5 g. per mole of silver halide but wider ranges of concentration can be useful, depending upon the particular organic compound, the size and nature of the silver halide crystals, the presence of other materials which may partially cover the surface of the silver halide crystal, and upon various other factors.
  • the silver halide is present in much higher concentration than in conventional emulsions and emulsion layers.
  • direct positive images are formed by a process constituting the subject matter of my application Ser. No. 236,420 filed Nov. 8, 1962 which process comprises i (a) Exposing imagewise to actinic radiation a photosensitive layer comprising silver halide crystals treated with an organic compound as described above,
  • the imagewise solution of the exposed silver halide/ organic compound stratum may be effected by the silver halide solvents commonly used as photographic fixing agents, e.g., sodium thiosulfate, alkali metal thiocyanate (e.g., sodium, potassium), concentrated solutions of potassium bromide, etc.
  • Reduction of the treated, residual silver halide may be accomplished by use of any chemical reducing agent capable of reducing silver ion to silver metal, e.g., hydroquinone, metol, sodium hydrosulfite and stannous chloride.
  • the function of the reducing agent may be enhanced by modifying the surface propenties of the treated, residual silver halide crystals by means of alcohol, thiourea, potassium iodide, etc.
  • the silver halide image may be toned, e.g., with sodium sulfide, sodium selenide, etc.
  • color images may be obtained by developing the treated, residual silver halide with a primary aromatic amine color developing agent in the presence of a color coupling compound either in the developing bath or previously incorporated in .the emulsion.
  • the present invention is not limited to a class of organic compounds with which the silver halide crystals are intimately associated or may be treated in preparing the novel compositions of this invention.
  • the utility of a specific 4-substituted-2-mercaptometathiazole compound or a salt thereof can be readily determined by a relatively simple test. Essentially, the test consists of two steps, Test A and Test B. In Test A, the candidate organic compound must render a dispersion of silver halide crystals insoluble in a silver halide solvent, i.e., an aqueous solution of sodium thiosulfate, at some pH between 1 and 13.
  • the candidate compound meets the insolubility requirements of Test A, it must also meet the requirements of Test B by forming with said dispersion of silver halide crystals a reaction product which, upon treatment with an aqueous solution of sodium hypochlorite, becomes soluble when subsequently treated with aqueous sodium thiosulfate.
  • Test B by forming with said dispersion of silver halide crystals a reaction product which, upon treatment with an aqueous solution of sodium hypochlorite, becomes soluble when subsequently treated with aqueous sodium thiosulfate.
  • a solution nearly saturated at 25 C. with a candidate organic compound is prepared using ethanol, acetone, dimethyl formamide, water or other suitable solvents. Depending on the solubility, (a solution concentration from 0.01 to 10 percent by weight is obtained. Twentyfive ml. of a silver chlorobromide dispersion containing 25 mg. of silver halide (calculated as silver bromide), prepared as described below, is treated with small increments (i.e., about 0.1 to 0.2 ml.
  • the silver halide dispersion insolubility is determined by taking a 0.5-ml. portion of the silver halide dispersion (after each incremental addition or" the candidate organic compound), adding about 0.1 to 0.2 ml. of 10% aqueous sodium thiosulfate solution and observing the turbidity afiter 3 seconds.
  • This mixture is vigorously stirred for 10 minutes at 95 F. and then the pH adjusted to 6.1:01 with aqueous sodium hydroxide solution.
  • the redispersed emulsion is then analyzed for silver halide content calculated as silver bromide and a dispersion made by diluting the appropriate amount with distilled water such that the dispersion contains 1 mg. calculated silver bromide per ml.
  • the emulsions may optionally contain any of the usual adjuvants customarily employed in silver halide systems so long as they do not interfere with the adsorption and complexing action of the essential ingredient of the invention.
  • the weight per individual crystal or grain is 7 Assuming a molecular weight of 157 for the mixed AgCl- AgBr crystals, and dividing this number by the weight per grain, gives which, multiplied by the 6.3 X10 grains per mole, gives a molar surface area of 4.6 10 or 4.6 10 square Angstroms.
  • Example III in a photographic emulsion coated on a film base support, it was found that 0.4 g. of MPT per mole of silver halide gave optimum results. This compares more closely with the theoretically determined amount of MPT required to cover the silver halide surface.
  • elements suitable for this novel process can be prepared by bathing a photographic film in a solution of an appropriate organic compound.
  • the silver halide crystals near the surface of the coated emulsion stratum are in contact with a higher concentration of the organic compound. Crystals farther from the surface, are treated with less of the organic compound and, if the rate of diffusion is sufiiciently slow, there may be considerably less of the organic compound (even approaching zero) reacting with the lower than with the surface silver halide crystals.
  • satisfactory results might be obtained with only a fraction, e.g., one-half, of the amount of the organic compound theoretically calculated as required to just cover the surface of a mole of the silver halide crystals.
  • Example 111 A lithographic emulsion having a silver halide composition of 30 mole percent AgBr and mole percent AgCl and having 20 grams of gelatin present per mole of silver halide for the steps of precipitation and ripening was freed of unwanted, soluble, byproduct salts by a coagulation and wash procedure as taught in US. Patent 2,489,341, wherein the silver halide and most of the gelatin were coagulated by an anionic wetting agent, sodium lauryl sulfate, using an acid coagulation environment. After washing, the emulsion coagulate was redispersed in water together with 47 g. of additional bulking gelatin per mole of silver halide, maintaining a pH of 60:01 while stirring 10 min.
  • Example VII A silver bromoiodide emulsion of the medical X-ray type was prepared by adding ammonia converted silver nitrate to a mixture of ammonium bromide and potassium iodide in gelatin. After ripening, the emulsion was coagulation washed. The final emulsion contained 1.6 mole percent silver iodide and 98.4 percent silver bromide. The washed curds were redispersed in gelatin to give a total of 200- g. of gelatin per mole of silver halide. To this emulsion was added 1,3 g.
  • Example 1 I Example 1 I
  • Example 1 I Example 1 I
  • the coated material showed more rapid fixing in an exposed than in an unexposed area such that upon intensification by subsequent re-exposure and chemical development as in Example III a positive metallic silver image was attained with maximum and minimum optical densities of 0.91 and 0.50.
  • the emulsion was ad- A direct-positive image was formed by the 5 10, 20 and 40-second exposures, i.e., imagewise density decreased with increasing exposure. However, when the exposure was increased to 80 sec., a negative image was formed, the system reversing or solarizing by increased exposure like conventional silver halide systems.
  • the film element was then rinsed 15 seconds in running water at 68 F., fixed 5 minutes at 68 F. in a potassium alum sodium thiosulfate fixing bath (the film required two minutes in the fixing bath to clear), washed 10 minutes and dried to give a slow and very weak negative silver image (Negative Image I).
  • Silver Coating Weights (mg/din?) Example Processing Time, sec. Unexposed Unexposed Exposed untreated Treated 10 see.
  • Example XIII A lithographic emulsion having a silver halide composition of 30 mole percent AgBr and 70 mole percent AgCl and having 20 grams of gelatin present per mole of silver halide for the steps of precipitation and ripening was freed of unwanted, soluble, by-product salts by a coagulation and wash procedure as taught in Waller et al., US. Patent 2,489,341, wherein the silver halide and most of the gelatin were coagulated by an anionic wetting agent, sodium lauryl sulfate, using an acid coagulation environment. Following the washing step the emulsion coagulate was redispersed by adding an aqueous solution containing g. of gelatin per mole of silver halide, adjusting the pH to about 6.0 and vigorously agitating for 65 minutes at 110 F.
  • Example XIV Example XIII was essentially repeated except the ethanol solution containing 0.08 gram of 2-mercapto-4- pentylthiazole was replaced with an ethanol solution of another Z-mercapto-4-substituted thiazole in the quantity indicated in the table below. Also, the amount of gelatin per mole of silver halide added at redispersion varied as indicated in the table:
  • Example XV Example XIII was essentially repeated except the ethanol solution containing 0.08 gram of 2-mercapto-4-penty1- thiazole was replaced with ml. of an aqueous solution of the sodium salt of 2-mercapto-4-phenylthiazole, prepared by dissolving 0.3 gram of 2-mercapto-4-phenyl thiazole in 2 ml. of l-molar sodium hydroxide and diluting with water to a volume of 600 ml. Also, the amount of gelatin per mole of silver halide added at redispersion was 47 grams rather than 80 grams. When tested as in Example XIII, the results were similar, a positive image being obtained from this coating.
  • the 2-mercapto-4-pentyl-, heptyl, undecyl, etc. thiazole compounds can be prepared by procedures like those for making lower homologues and analogues. Thus, they can be made by the procedures of Ritter et al., J. Am. Chem. Soc., vol. 70, pp. 3419-21, from NH CSSNH and the appropriate N-alkyl chloromethyl ketone, etc.
  • the silver halide photosoluble elements of this invention differ from conventional silver halide emulsions containing antifogging agents in that the insolubilizing compounds used in the photosoluble elements are present in substantially greater than fog-inhibiting amounts, the latter amounts being the maximum quantity which provides low fog without serious loss in speed and photographic quality. For this reason it is not practical to use photosoluble elements in place of ordinary silver halide photograpmc materials.
  • photosoluble elements When photosoluble elements are exposed and processed normally, development proceeds slowly and incompletely to give a negative silver image having much less speed and lower density. In addition, 1 .ing is slower and may be incomplete for practical fixing times. Thus, photosoluble elements require longer conventional processing times and give slower speed, inferior quality images when compared to ordinary silver halide photographic elements.
  • a primary advantage is the simplicity of their preparation. They can be exposed and processed to images under ordinary room light conditions.
  • the photographic processes applicable to the new products of the invention likewise have advantages over previously known systems based on selective reduction of exposed silver halide for forming either direct positive or negative images Without resorting to the special effects and sensitizing procedures previously used for preparing such images.
  • this present process is not limited to the use of certain photographic developing agents but may be accomplished by using a wide range of reducing agents. Many such compounds are of very low cost and can be used to form images of much higher covering power than customary, thus elfecting important economies in processing, as well as greatly increasing the efiiciency of the silver image with a resultant increase in sensitivity.
  • Another advantage of this invention is that it provides new elements for forming silver images that do not require special equipment but instead can be used with conventional equipment and apparatus.
  • a further advantage is that the elements can be used successfully by photographic technicians and photographers of ordinary skill.
  • a still further advantage is that the elements can be processed with conventional reducing agents, e.g., developers and fixing agents.
  • a still further advantage is that the new elements can be used to produce images without selective reduction.
  • a photographic silver halide emulsion layer wherein any heavy metal salt present is a silver halide comprising, before exposure to actinic radiation, light-sensitive silver halide crystals having associated therewith in substantially greater than fog-inhibiting amounts a silver mercaptide of a mercapto compound of the formula:
  • R is a hydrocarbon nucleus of 4-12 carbon atoms
  • said silver mercaptide being of lower solubility in Water than silver chloride and the silver halide crystals so associated with the silver mercaptide dissolving more slowly in aqueous sodium thiosulfate than untreated silver halide crystals at a predetermined pH, the mercapto compound forming the mercaptide being present in such an amount, in terms of the ratio of its Weight to the surface area of said silver halide crystals, that when admixed in such ratio with an aqueous silver chlorobromide (70/30 mole percent) gelatin dispersion containing 57 g. of gelatin per mole Ag and .57 mg.
  • said silver chlorobromide dispersion is treated with 10%, by weight, aqueous sodium thiosulfate (so that the resulting mixture contains 0.29 mg. of silver and mg. of sodium thiosulfate), at least three times the amount of silver chlorobromide remains undissolved as in a similar dispersion successively treated with 5%, by weight, aqueous sodium hypochlorite and 10%, by Weight, aqueous sodium thiosulfate (so that the resulting mixture contains 0.29 mg. of silver, 25 mg. of sodium hypochlorite and 100 mg. of sodium thiosulfate), after vigorous agitation of the dispersions for 30 seconds at 25 C.
  • a photographic silver halide emulsion layer wherein any heavy metal salt present is a silver halide comprising, before exposure to actinic radiation, light-sensitive silver halide crystals having associated therewith in substantially greater than fog-inhibiting amounts a silver mercaptide of a mercapto compound of the formula:
  • R is an unsubstituted hydrocarbon radical of 6-10 carbon atoms having a cyclic hydrocarbon radical of six carbon atoms attached through a cyclic carbon atom thereof to the 4-carbon atom of the thiazole ring, said silver mercaptide being of lower solubility in water than silver chloride and less soluble in 10% aqueous sodium thiosulfate than untreated silver halide crystals at a predeter-' mined pH, said mercapto compound forming the mercap tide being present in such an amount, in terms of the ratio of its weight to the surface area of said silver halide crystals, that when admixed in such ratio with an aqueous silver chlorobromide (70/30 mole percent) gelatin dis persion containing 57 g.
  • a photographic silver halide emulsion layer wherein any heavy metal salt present is a silver halide comprising, before exposure to actinic radiation, light-sensitive silver halide crystals having associated therewith in substantially greater than fog-inhibiting amounts a silver mercaptide of a mercapto compound, said silver mercaptide and its concentration relative to the surface area of the silver halide is characterized in that when tested in a gelatino-silver chlorobromide emulsion (70% silver chloride and 30% silver bromide) which is (a) applied to a photographic film base at a coating weight of 100 mg./dm. of silver halide and 100 mg./dm. of gelatin,
  • H 10 to make 900 ml. Adjust pH to 4.8i0.1 with 3 N H 80 or 3 N NaOH. H O to make 1 liter and (d) washed in water for 5 minutes at 20 C. and
  • a photographic silver halide composition wherein any heavy metal salt is a silver halide comprising, before exposure to actinic radiation, light-sensitive silver halide crystals having associated therewith in substantially greater than fog-inhibiting amounts a silver mercaptide of a mercapto compound of the formula:
  • silver chlorobromide dispersion is treated with 10%, by weight, aqueous sodium thiosulfate (so that the resulting mixture contains 0.29 mg. of silver and 100 mg. of sodium thiosulfate), at least three times the amount of silver chlorobromide remains undissolved as in a similar dis persion successively treated with 5%, by weight, aqueous sodium hypochlorite and 10% by weight, aqueous sodium thiosulfate (so that the resulting mixture contains 0.29 mg. of silver, 25 mg. of sodium hypochlorite and 100 mg. of sodium thiosulfate), after vigorous agitation of the dispersions for 30 seconds at 25 C.
  • a photographic silver halide emulsion layer comprising, before exposure to actinic radiation, light-sensitive silver halide crystals having associated therewith in substantially greater than fog-inhibiting amounts, and from one-half the amount required to just cover the surface of a mole of the silver halide crystals to 0.75 gram per mole of said crystals of 2-mercapto-4-phenylthiazole, said compound thereby being present in such an amount, in terms of the ratio of its Weight to the surface area of said silver halide crystals, that when admixed in such ratio with an aqueous silver chlorobromide 30 mole percent) gelatin dispersion containing 57 g. of gelatin per mole Ag and .57 mg.
  • said silver chlorobromide dispersion is treated with 10%, by weight, aqueous sodium thiosulfate (so that the resulting mixture contains 0.29 mg. of silver and mg. of sodium thiosulfate), at least three times the amount of silver chlorobromide remains undissolved as in a similar dispersion successively treated with 5%, by weight, aqueous sodium hypochlorite and 10%, by weight, aqueous sodium thiosulfate (so that the resulting mixture contains 0.29 mg. of silver, 25 mg. of sodium hypochlorite and 100 mg. of sodium thiosulfate), after vigorous agitation of the dispersions for 30 seconds at 25 C.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Silver Salt Photography Or Processing Solution Therefor (AREA)
  • Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)
  • Thiazole And Isothizaole Compounds (AREA)
  • Photosensitive Polymer And Photoresist Processing (AREA)

Description

United States Patent 3,155,519 PHQTQGRAPHIC CQMPGSITIGNS, LAYERS AND ELEMENTS Ralph Kingsley Biake, Westiield, N.J., assignor to E. L du Pont de Nernours and Company, Wilmington, Del., a corporation of Delaware No Drawing. Filed Oct. 21, 1963, Ser. No. 317,824 12 Claims. (Cl. 96107) This invention relates to photography and more particularly to new image-yielding photographic silver halide emulsion layers and to photographic elements embodying such layers.
The present application is a continuation-in-part of my copending application Ser. No. 236,412, filed Nov. 8, 1962.
An object of this invention is to provide new and useful photographic silver halide layers and elements. Another object is to provide such layers which can be used to form direct positives. Yet another object is to provide such layers and elements which cannot be readily fixed during normal processing periods prior to exposure. A further object is to provide such layers which are easy to make, embody relatively inexpensive chemicals and are dependable in use. Still additional objects will be apparent from the following description of the invention.
The photographic layers and elements, e.g., films, plates and papers embodying such layers, of thi invention comprise, before exposure to actinic radiation, light-sensitive silver halide crystals, preferably having at least by weight of silver chloride, having associated therewith in substantially greater than fog-inhibiting amounts, a silver mercaptide of a mercapto compound of the formula wherein R is a hydrogen nucleus of 4-12 carbon atoms. Thus, R may be alkyl of 412 carbon atoms, e.g., isobutyl, heptyl and undecyl; cycloalkyl, e.g., cyclohexyl; and aryl, e.g., phenyl. The hydrocarbon nucleus can contain substituent groups; suitable substituted hydrocarbon radicals include p-bromophenyl and p-nitrophenyl. The mercapto compounds can be initially added as the free SH compound or as the sodium, potassium or ammonium salt.
According to an important and preferred aspect of the invention, R is an unsubstituted hydrocarbon radical of 6l0 carbon atoms and has a cyclic hydrocarbon radical of six carbon atoms attached through a cyclic carbon of said radical to the 4-carbon atom of the thiazole ring. Suitable radicals of the latter type include cyclohexyl, methylcyclohexyl, phenyl, tolyl and alpha-naphthyl.
The amount of the silver mercaptide present in the photographic silver halide layer should be sufficient to protect the silver halide crystals so that the unexposed layer cannot be fixed by conventional fixing conditions, i.e., at normal times and temperatures and concentrations of silver solvent.
In the novel photographic silver halide layers of the invention the protective silver mercaptide and its concentration relative to the surface area of the silver halide is characterized in that when tested in a gelatino-silver chloro-bromide emulsion (70% silver chloride and 30% silver bromide) which is (a) Applied to a photographic film base at a coating weight of 100 mg./dm. of silver halide and 100 mg./dm. of gelatin,
(b) Given an exposure of no more than 60,000 metercandle seconds to a light of a color temperature of 2800 K.,
ice
(c) Bathed for 30 seconds at 20 C. in the following solution:
Na2SgO3 (anhyd.) g 100 Na SO (anhyd.) g 9.8 Borax (Na B O -10H O) g 11.8 Acetic acid (glacial) ml 7.8 Potassium alum, KAl(SO '12H O g 13.1 Potassium acetate g 10 1-1 0 to make 900 ml. Adjust pH to 4.8:01 with 3 N H or 3 N NaOH. H O to make 1 liter.
and (d) washed in water for 5 minutes at 20 C. and dried in air,
At least 25 mg./dm. of silver halide remains in the unexposed areas while no more than 1 mg./dm. of silver halide remains in the area having been given said exposure.
The silver mercaptide, which is less soluble in water than silver chloride, is further characterized in that when such silver mercaptide is formed by addition of an organic mercaptan or ion thereof to an aqueous dispersion of silver halide, said silver mercaptide protects the silver halide from solution to the extent that at least three times the amount of silver halide remains undissolved as compared to (a) the untreated silver halide dispersion or (b) the mercaptan-treated silver halide dispersion which has subsequently been treated with 5% aqueous sodium hypochlorite, when all three of said dispersions are treated individually with equal amounts of 10% aqueous sodium thiosulfate and agitated identically for 30 seconds at 25 C.
Preferably, the silver halide crystals are dispersed in a water-permeable organic colloid to form a light-sensitive photographic silver halide emulsion. The 4-hydrocarbon substituted-Z-mercaptometathiazole can be added to the silver halide emulsion while the latter is in the liquid state or the emulsion may be coated on a suitable support and the resulting element bathed or impregnated with a solution, e.g., an alcoholic solution of the organic compound. In the working examples below, the amount of organic compound in the silver halide emulsion is from about 0.4 to 5 g. per mole of silver halide but wider ranges of concentration can be useful, depending upon the particular organic compound, the size and nature of the silver halide crystals, the presence of other materials which may partially cover the surface of the silver halide crystal, and upon various other factors.
The gelatin:silver halide ratio is quite flexible and may vary from 3 :1 to 1:30 depnding on the particular organic compound and intended use for the emulsion layer.
In one commercially practical aspect of the invention, the silver halide is present in much higher concentration than in conventional emulsions and emulsion layers.
In an important use of the products of the invention, direct positive images are formed by a process constituting the subject matter of my application Ser. No. 236,420 filed Nov. 8, 1962 which process comprises i (a) Exposing imagewise to actinic radiation a photosensitive layer comprising silver halide crystals treated with an organic compound as described above,
(12) Treating the exposed layer in a solution of a silver halide solvent to remove soluble silver halide in the exposed image areas, thus forming a positive silver halide image, and preferably (0) Washing the resulting layers.
If desired, the silver halide image may be viewed directly, e.g., by projection (if on a transparent support) or it may be intensified by (d) Converting the residual silver halide to silver by treatment in a fogging developer, e.g., a high pH l-phenyl- 4-rnethyl-3-pyrazolidone/hydroquinone developer containing iodide ion or by fogging the emulsion by exposure to light and then treating with a silver halide reducing agent, e.g., a conventional silver halide developer, and
(e) Washing the developed layer to reveal a positive silver image in the original non-exposed areas.
The imagewise solution of the exposed silver halide/ organic compound stratum may be effected by the silver halide solvents commonly used as photographic fixing agents, e.g., sodium thiosulfate, alkali metal thiocyanate (e.g., sodium, potassium), concentrated solutions of potassium bromide, etc. Reduction of the treated, residual silver halide may be accomplished by use of any chemical reducing agent capable of reducing silver ion to silver metal, e.g., hydroquinone, metol, sodium hydrosulfite and stannous chloride. The function of the reducing agent may be enhanced by modifying the surface propenties of the treated, residual silver halide crystals by means of alcohol, thiourea, potassium iodide, etc. The silver halide image may be toned, e.g., with sodium sulfide, sodium selenide, etc. In addition, color images may be obtained by developing the treated, residual silver halide with a primary aromatic amine color developing agent in the presence of a color coupling compound either in the developing bath or previously incorporated in .the emulsion.
The present invention is not limited to a class of organic compounds with which the silver halide crystals are intimately associated or may be treated in preparing the novel compositions of this invention. The utility of a specific 4-substituted-2-mercaptometathiazole compound or a salt thereof can be readily determined by a relatively simple test. Essentially, the test consists of two steps, Test A and Test B. In Test A, the candidate organic compound must render a dispersion of silver halide crystals insoluble in a silver halide solvent, i.e., an aqueous solution of sodium thiosulfate, at some pH between 1 and 13. If the candidate compound meets the insolubility requirements of Test A, it must also meet the requirements of Test B by forming with said dispersion of silver halide crystals a reaction product which, upon treatment with an aqueous solution of sodium hypochlorite, becomes soluble when subsequently treated with aqueous sodium thiosulfate. The following practical tests are provided in further exemplification of the invention and include specific concentrations of solutions, times, etc., so that suitable organic compounds may be readily and positively identified.
TEST A A solution nearly saturated at 25 C. with a candidate organic compound is prepared using ethanol, acetone, dimethyl formamide, water or other suitable solvents. Depending on the solubility, (a solution concentration from 0.01 to 10 percent by weight is obtained. Twentyfive ml. of a silver chlorobromide dispersion containing 25 mg. of silver halide (calculated as silver bromide), prepared as described below, is treated with small increments (i.e., about 0.1 to 0.2 ml. at a time) of the said candidate solution under safelight conditions (Wratten 1A filter or equivalent) until the silver halide dispersion either is rendered insoluble in 10% aqueous sodium thiosulfate or the candidate is found not to cause insolubilization. Generally insolubilization will occur upon the addition of 0.05 g. or less of said candidate compound, calculated as the pure compound. Compounds which must be used in substantially greater quantities than this, e.g., 1-2 g. to efiect insolubilization are considered less preferred compounds. The silver halide dispersion insolubility is determined by taking a 0.5-ml. portion of the silver halide dispersion (after each incremental addition or" the candidate organic compound), adding about 0.1 to 0.2 ml. of 10% aqueous sodium thiosulfate solution and observing the turbidity afiter 3 seconds.
As a control, one should use 25 ml. of water to which small increments of the candidate solution are added. Half-milliliter portions of the control are treated in the same manner with the sodium thiosulfate solution. The
presence of visual turbidity relative to the control is sufficient to satisfy the definition of insolubility in this test.
This test may be repeated for various pH increments from 1 to 13. Although there is some optimum pH value at which the test is most sensitive, this is not a sharp maximum which must be precisely attained. Rather, it has been found that there is a fairly broad range of pH values (eg 2.0 to 3.0 pH units) over which the test has a satisfactory sensitivity. In practice, the silver halide dispersion might be tested without adjustment (e.g. at pH 5.0 to 7.0) and if insolubilization occurs here, Test A is completed. If there is no insolubilization, the test is repeated at a higher pH (e.g., from pH 10-13). If there is still no insolubilization, the test is conducted with emulsion adjusted to a lower pH (e.g., about pH l-3). Thus three different pH values represents a practical maximum number which must be investigated to determine whether or not insolubilization will occur.
TEST B An organic compound capable of insolubilizing a silver halide dispersion according to Test A is now ready for the next test, which again will be conducted under safelight conditions. To the above silver halide dispersion, there is added the minimum amount of a solution of the candidate organic compound found necessary for insolubilization. Half-milliliter samples of the dispersion (containing 0.5 mg. AgBr or 0.29 mg. Ag) are placed in two test tubes. To one sample is added 0.5 ml. of water; to the other is added 0.5 ml. of a 5% by weight aqueous solution of sodium hypochlorite (containing 25 mg. sodium hypochlorite). Next, there is added to both samples, 1.0 ml. of an aqueous 10% by weight solution of sodium thiosulfate (containing mg. sodium thiosulfate). If, after standing for up to thirty seconds, the sample treated with sodium hypochlorite clarifies (or becomes less turbid) relative to the control sample, the candidate organic compound meets the requirements of Test B and it is satisfactory for use as disclosed in this invention.
SILVER HALIDE DISPERSION PREPARATION Dispersion I.-The silver halide dispersion disclosed in Tests A and B is prepared according to the following specifications. In red light, 30 g. of photographic grade gelatin is soaked in 1100 ml. of distilled water for 10 minutes. The temperature is then raised to F. and 100 g. of solid ammonium chloride added. The mixture is stirred at 120 F. and after the ammonium chloride is completely dissolved, a solution made by diluting 500 ml. of 3 N silver nitrate with 2000 ml. of distilled water is added while stirring the solution for 5 seconds. This mixture is held at 120 F. for 4 minutes with stirring, and then ml. of 3 N ammonium bromide added (30 mole percent) in 10 seconds. The mixture is held an additional 15 minutes at 120 F. with stirring and then cooled to 100 F. A mixture of 75 g. of the sodium salt of technical lauryl alcohol sulfate (a white powder) and 7 ml. of 3 N sulfuric acid is added in 10 seconds to the silver chlorobromide, stirring continued for one minute and then the mixture allowed to settle. The supernatant liquid is decanted and replaced by 2000 ml. of distilled water containing 4 g. of sodium chloride. This mixture is stirred for 5 minutes at 100 F., allowed to settle and decanted again. Two hundred ml. of distilled water is added to the silver halide curds and the temperature adjusted to 95 F. This mixture is vigorously stirred for 10 minutes at 95 F. and then the pH adjusted to 6.1:01 with aqueous sodium hydroxide solution. The redispersed emulsion is then analyzed for silver halide content calculated as silver bromide and a dispersion made by diluting the appropriate amount with distilled water such that the dispersion contains 1 mg. calculated silver bromide per ml.
Dispersed crystals of silver halide, treated with an appropriate amount of a suitable organic compound are affected by exposure of a portion of said crystals to actinic radiation, e.g., ultraviolet, visible, infrared, X- radiation, etc., to such an extent that at least of the less soluble crystals remain when 90% of the more soluble crystals dissolve when treated in 10% by weight aqueous sodium thiosulfate solution.
In place of part of the gelatin, other natural or synthetic water-permeable organic colloid binding agents can be used and in some cases such binders can be used alone. Such agents include water-permeable or water-soluble polyvinyl alcohol and its derivatives, e.g., partially hydrolyzed polyvinyl acetates, polyvinyl ethers and acetals containing a large number of intralinear groups, hydrolyzed interpolymers of vinyl acetate and unsaturated addition polymerizable compounds such as maleic anhydride, acrylic and methacrylic acid esters and styrene. Suitable such colloids of the last-mentioned type were disclosed in US. Patents 2,276,322; 2,276,323 and 2,397,866. The useful polyvinyl acetals include polyvinyl acetaldehyde acetal, polyvinyl butyraldehyde acetal and polyvinyl sodium o-sulfobenzaldehyde acetal. Other useful colloid binding agents which can be used include the poly-N-vinyllactams of Bolton US. Patent 2,495,918, various polysaccharides, e.g., dextran, dextrin, etc., the hydrophilic copolymers in Shacklett US. Patent 2,833,650, hydrophilic cellulose ethers and esters, and polymers of acrylic and methacrylic esters and amides. Also, it has been found practical to treat silver halide layers on a base material in the essential absence of a binder, e.g., by chemical or vacuum deposition.
The emulsions may optionally contain any of the usual adjuvants customarily employed in silver halide systems so long as they do not interfere with the adsorption and complexing action of the essential ingredient of the invention.
The emulsions can be coated on any suitable support, e.g., cellulose esters, cellulose mixed esters; superpolymers, e.g., polyvinyl chloride (co) vinyl acetate, polyvinyl acetals, butyrals; polystyrene; polyamides, e.g., polyhexamethylene adipamide, polyesters, e.g., polycarbonates, polyethylene terephthalate, polyethylene terephthalate/isophthalate, esters formed by condensing terephthalic acid and its derivatives, e.g., dimethyl terephthalate with propylene glycol, diethylene glycol, tetramethylene glycol, cyclohexane-1,4-dimethanol (hexahydro-p-xylene dialcohol); paper, metal, glass, etc.
As disclosed earlier, the desirable concentration of the selected organic compound depends on many factors such as the size and solubility of the organic compound, the nature of its reaction with silver halide, the size and nature of the silver halide crystals, the presence of other materials which may react with or be adsorbed to the surface of the silver halide, etc. In Example VI of Ser. No. 236,420, a number of compounds are disclosed which were tested in a dispersion of silver halide crystals wherein the average grain size was 0.35 (micron) in diameter, therefore about 0043a in volume, assuming cubic grains. The silver halide comprised 70 mole precent silver chloride and mole percent silver bromide, with a specific density of about 5.7 g./cc. or 5.7 1-0 g./,u The weight per individual crystal or grain is 7 Assuming a molecular weight of 157 for the mixed AgCl- AgBr crystals, and dividing this number by the weight per grain, gives which, multiplied by the 6.3 X10 grains per mole, gives a molar surface area of 4.6 10 or 4.6 10 square Angstroms.
' A particularly preferred organic compound is 2-mercapto-4-phenylthiazole (hereinafter to be referred to as MPT). Assuming that a single molecule of MPT could occupy an area of 28 square Angstroms, it would require 1.5 10 molecules to occupy a molor surface area of silver halide. With a molecular weight of 193, this would require to just cover the surface of one mole of the silver halide crystals. In Example VI of Ser. No. 236,420, 1.2 10 g. MPT insolubilized 2.5 X 10* g. of silver halide of average molecular weight 157. Therefore according to experimental data (test tube results) it would require to insolubilize one mole of the silver halide. More significantly, as disclosed in Example III in a photographic emulsion coated on a film base support, it was found that 0.4 g. of MPT per mole of silver halide gave optimum results. This compares more closely with the theoretically determined amount of MPT required to cover the silver halide surface.
As shown in various examples below, e.g. Example I, elements suitable for this novel process can be prepared by bathing a photographic film in a solution of an appropriate organic compound. In this embodiment, the silver halide crystals near the surface of the coated emulsion stratum are in contact with a higher concentration of the organic compound. Crystals farther from the surface, are treated with less of the organic compound and, if the rate of diffusion is sufiiciently slow, there may be considerably less of the organic compound (even approaching zero) reacting with the lower than with the surface silver halide crystals. In such elements, satisfactory results might be obtained with only a fraction, e.g., one-half, of the amount of the organic compound theoretically calculated as required to just cover the surface of a mole of the silver halide crystals.
With regard to Tests A and B and Dispersion I, by reference to the above text or by calculation, it can be readily determined that the 2-mercapto-4-hydrocaroon substituted thiazole disclosed herein should be present in such an amount, in terms of the ratio of its weight to the surface area of said silver halide crystals, that when admixed in such ratio with an aqueous silver chlorobromide (70/30 mole percent) gelatin emulsioncontaining 57 g. of gelatin per mole Ag and .57 mg. of Ag/mL, and said silver chlorobromide dispersion is treated with 10%, by weight, aqueous sodium thiosulfate (so that the resulting mixture contains 0.29 mg. of silver and mg. of sodium thiosulfate), at least three times the amount of silver chlorobromide remains undissolved as compared with a similar dispersion successively treated with 5%, by weight, aqueous sodium hypochlorite and 10%, by Weight, aqueous sodium thiosulfate (so that the resulting mixture contains 0.29 mg. of silver, 25 mg. of sodium hypochlorite and 100 mg. of sodium thiosulfate), after vigorous agitation of the dispersions for 30 seconds at 25 C.
The invention is useful with silver halide layers free from or containing a water-permeable colloid binding agent.
Test C of my prior application, Ser. No. 236,420, can be used to determine the utility of compounds of this case. According to Test C, a 0.5 ml. portion of the insolubilized dispersion of Test A under a safelight is placed in a 12 75 mm. Pyrex test tube 3 inches from a No. 2 reflectoflood lamp. This dispersion is exposed to the lamp for up to 10 minutes. A control consists of a 0.1 ml. portion of the insolubilized dispersion from Test A. Two-tenths ml. of 10% aqueous sodium thiosulfate is added to each dispersion and is compared under safelight conditions. Any reduction in turbidity of the dispersion exposed to the lamp compared to the unexposed control after treatment with aqueous sodium thiosulfate shows that photosolutilization occurs.
The invention will be further illustrated by but is not intended to be limited to the following examples.
Example I A photographic element was prepared by coating an aqueous gelatin dispersion of silver chlorobromide (70 mole percent silver chloride and 30 mole percent silver bromide) on a film base prepared as described in Example IV of Alles US. Patent 2,779,684. The dispersion had a ratio of silver halide to gelatin of 28:1 by weight and was coated at a pH of 6 at a rate of 116 milligrams of silver halide per square decimeter. After drying, the element was bathed for about 30 seconds in an ethanol-water solution of Z-mercapto-4-phenylthiazole having a pH of 5.1 and dried. The solution of 2-mercapto-4-phenylthiazole was prepared by diluting ml. of a stock solution (1 gram of the compound made up to 100 ml. in ethanol) with an additional 20 ml. of ethanol and ml. of water. The dried element was then exposed behind a photographic transparency for seconds to the radiation from a General Electric 2-A photoflood lamp at a distance of about 6-10 inches. The exposed element was then immersed in a 12.8% aqueous solution of sodium thiosulfate for 30 seconds resulting in removal of the silver salt in the exposed areas. Subsequently, the fixed film was then rinsed briefly in water and bathed in a rapid acting fogging photographic developer solution comprising 1-pheny1-4- methyl-3-pyrazolidone and hydroquinone as reducing agents to which there had been added potassium iodide and a direct positive image formed. All of the above operations were carried out in ordinary fluorescent room illumination.
Where a more sensitive product is prepared by appropriate selection of such factors as grain size, silver halide composition, etc., it may be desirable to use conventional photographic darkroom handling of the element prior to the image exposure. During the developing step, the treated element is converted into an exact reproduction (i.e., direct positive image) of the original transparency. After brief washing in water and drying, it is satisfactory for use in any application where an exact reproduction is desired, e.g., in the graphic arts field, for a projection transparency, etc.
Example II A photographic element was prepared by coating an aqueous gelatin dispersion of silver bromoiodide (98.86 mole percent silver bromide and 1.14 mole percent silver iodide) on a cellulose acetate film base and drying the coating. The dispersion had a ratio of silver halide to gelatin of 1.00:1.03 by weight and was coated at a pH of 6.2 at a rate of 105 milligrams of silver halide per square decimeter. After drying, the element was bathed for 30 seconds in a dilute aqueous solution of Z-mercapto- 4-phenylthiazole and dried. The solution of 2-mercapto- 4-phenylthiazole was prepared by diluting 5 ml. of the stock solution used in Example I with 10 ml. of ethanol and ml. of water, and had a pH of 4.60. The element was exposed as in Example I except that the exposure time was increased to seconds. It was then bathed in the sodium thiosulfate solution of that example for 60 seconds, rinsed briefly in water, bathed in the same develop for 60 seconds, all operations being carried out in ordinary fluorescent room illumination. A direct positive image was formed in the same manner as in Example I. The same course of treatment applied to a commercial panchrornatically-sensitized emulsion gave comparable results.
In connection with the above examples, it has been found that the pH of the treating solution used to initially bathe the film has a striking effect. With very low pH the effect of the treatment is minimized or completely eliminated. For example, with the compound of Example I the eflect of the treatment can be eliminated if the treating solution has a pH about 1 or lower. While all of the compounds produce desirable results over a wide pH range, each compound apparently has an optimum pH range which is most effective. It will be apparent to one skilled in the art that simple tests can be run to establish the best pH conditions for operation.
Example 111 A lithographic emulsion having a silver halide composition of 30 mole percent AgBr and mole percent AgCl and having 20 grams of gelatin present per mole of silver halide for the steps of precipitation and ripening was freed of unwanted, soluble, byproduct salts by a coagulation and wash procedure as taught in US. Patent 2,489,341, wherein the silver halide and most of the gelatin were coagulated by an anionic wetting agent, sodium lauryl sulfate, using an acid coagulation environment. After washing, the emulsion coagulate was redispersed in water together with 47 g. of additional bulking gelatin per mole of silver halide, maintaining a pH of 60:01 while stirring 10 min. at F. Assuming that 10 g. of gelatin was lost during washing, the resulting emulsion contained about 57 g. of gelatin per mole of silver halide. The emulsion was brought to 2320 g. by addition of water and the temperature adjusted to F. Four-tenths of a gram of MFT (2-mcrcapto-4-phenylthiazole) was added per mole of silver halide from a 1% by weight ethanol solution. Chrome alum hardener was added and the emulsion was diluted with water to a total weight of 2334 g. per mole of silver halide. This emulsion was applied at a coating weight of 46 mg. of silver per square decimeter on 0.004 inch thick polyester photographic film base as described in Example I. The coating, after imagewise exposure, showed a greater rate of fixing in a 1.0 N (0.5 molar) aqueous sodium thiosulfate in exposed areas than in the unexposed areas so as to form a positive silver halide image. Subsequent flashing to white light, followed by treatment with a reducing agent (a conventional photographic developing solution containing 1-phenyl-4-methyl-3 pyrazolidone and hydroquinone), resulted in the formation of a positive image of metallic silver.
Example IV Optical Density Weight of MP1 Uncxposed Heavily Exposed gJmole of silver g./mole of silver g g l mole of silver mole of silver s s m De-HO UIO'IOO Example V A silver bromide emulsion was prepared by adding one mole of 1.5 N AgNO to 1.2 moles of a solution of 0.70 N KBr containing 33 g. of gelatin. After ripening 10 minutes at F. the emulsion was coagulated by the addition of a 12% aqueous solution of a water-soluble, acid-soluble partial acetal of polyvinyl alcohol and osulfobenzaldehyde and consisting of 5 g. of sulfonate sulfur per 100 g. of polymer, followed by the addition of sulfuric acid to lower the pH to 2.6. An aqueous solution containing 7.2 g. of KBr was then added and the curds were redispersed at 95 F. for 10 minutes with high shear stirring. Sodium hydroxide was added to adjust the pH to 4.1 and redispersion was continued for 30 minutes. The curds were then dispersed in an aqueous 16% by weight gelatin solution to give a total of 300 g. gelatin per mole of silver bromide. Then 2-mercapto-4-pheny1- thiazole was added from a 1% ethanol solution to give a total of 0.6 g. per mole of silver bromide. The emulsion was adjusted to 2700 g. with water after addition of a chrome alum hardening agent. The emulsion was applied at a coating Weight of 35 mg. of silver per square decimeter. The coating showed more rapid fixing in an exposed area than in an unexposed area such that upon intensification by subsequent re-exposure and chemical development as in Example 11 a positive metallic silver image was attained with a mixmum optical density of 1.26 and a minimum optical density of 0.35.
Example VI A silver chloride emulsion was prepared in the same manner as in Example V, except KCl was used instead of KBr at precipitation and redispersion. The KCl at precipitation was present in an amount of 1.08 moles per mole of silver nitrate. The curds were dispersed in 17% gelatin to give a total of 94 g. gelatin per mole of silver bromide. MPT (12 mercapto 4 phenylthiazole) was added from a 1% ethanol solution to give a total of 1.0 g. per mole of silver chloride. justed to a final weight of 1950 g. with Water after the addition of chrome alum as a hardening agent. The emulsion was applied at a coating weight of 35 mg. of silver per square decimeter. The coating showed more rapid fixing in an exposed area such that upon intensification by subsequent re-exposure and chemical development as in Example III a positive metallic silver image was attained with maximum and minimum optical densities of 1.21 and 0.18.
Example VII A silver bromoiodide emulsion of the medical X-ray type was prepared by adding ammonia converted silver nitrate to a mixture of ammonium bromide and potassium iodide in gelatin. After ripening, the emulsion was coagulation washed. The final emulsion contained 1.6 mole percent silver iodide and 98.4 percent silver bromide. The washed curds were redispersed in gelatin to give a total of 200- g. of gelatin per mole of silver halide. To this emulsion was added 1,3 g. of Z-mercapto-4-phenylthiazole and the emulsion was applied to the support described in Example 1 I at a coating weight of 35 mg. of silver per square decimeter. The coated material showed more rapid fixing in an exposed than in an unexposed area such that upon intensification by subsequent re-exposure and chemical development as in Example III a positive metallic silver image was attained with maximum and minimum optical densities of 0.91 and 0.50.
Example VIII A photographic layer was made by evaporating silver chloride onto the film base described in Example I, using a High Vacuum Evaporator, Model No. 803 (Optical Film Engineering Co.). The vacuum apparatus employed a tantalum ribbon and operated at a pressure of 3 10 microns of mercury. Using about 280 milligrams of AgCl at a distance of 24 cm. from the film base, a coating weight of AgCl of about 4 mg./dm. was obtained. The vacuum-coated film was bathed for sec. in the ethanol-water (25/10) solution of 2-mercapto-4-phenylthiazole of Example I, dried and exposed stepwise for 5, 10, 20, 40 and 80 sec. to a photoflood lamp (General Electric 2-A) at a distance of 6 inches. The exposed element was then immersed in 12.8% aqueous sodium thiosulfate for sec., rinsed in water for 10 sec. and then bathed in a developer solution as described in Example I.
The emulsion was ad- A direct-positive image was formed by the 5 10, 20 and 40-second exposures, i.e., imagewise density decreased with increasing exposure. However, when the exposure was increased to 80 sec., a negative image was formed, the system reversing or solarizing by increased exposure like conventional silver halide systems.
Example IX Example II was essentially repeated except that (a) the element was bathed for 60 seconds (rather than 30 seconds) in the solution of 2-mercapto-4-phenylthiazole, (b) the sodium thiosulfate fixing solution was replaced with an aqueous solution containing, on a liter basis, 150 g. KCNS and ml. of 1 molar Na CO and the fixing time was extended to 2 minutes, and (c) safe lights were used throughout all operations up to the second treatment with developer solution, with ordinary fluorescent room illumination being used subsequently. A direct position image was formed, similar to that of Example II.
Example X A photosoluble element was prepared from a conventional orthochromatic fully sensitized lithographic gelatino silver halide film (comprising mole percent silver chloride and 30 mole percent silver bromide) having a coating weight of about milligrams per square decimeter silver halide. The film support was the same as that described in Example I. Under safelight conditions, this film was bathed for 30 seconds in the dilute ethanolwater solution of 2-mercapto-4-phenylthiazole described in Example I. The dried element was exposed behind a square-root-of-two photographic step wedge for 10 seconds to the radiation from a General Electric 2-A photoflood lamp, operating at 115 volts and at a distance of 6 inches. The exposed element was then immersed in a 12-18% aqueous solution of sodium thiosulfate for seconds resulting in removal of the silver salt in the exposed areas. The fixed film was subsequently rinsed briefly in water and then, under white room lights, bathed in a rapid acting photographic developer comprising 1- phenyl-4-methyl-3-pyrazolidone and the hydroquinone as reducing agents. A direct positive step-wise silver image formed.
Another sample of the photosoluble element (bathed in the above solution of 2-mercapto-4-phenylthiazole) was exposed behind a square-root-of-two step wedge for 3 seconds to the radiation from the above described photofiood lamp operating at 25 volts and at a distance of 2 feet.
The exposed element was then developed for 2 minutes at 68 F. in the following conventional photographic developer:
G. Monomethyl-p-aminophenosulfate 3.0 Hydroquinone 9.0 Na sO anhydrous 50.0 K CO 50.0 KBr 4.5 Water to make 1 liter.
The film element was then rinsed 15 seconds in running water at 68 F., fixed 5 minutes at 68 F. in a potassium alum sodium thiosulfate fixing bath (the film required two minutes in the fixing bath to clear), washed 10 minutes and dried to give a slow and very weak negative silver image (Negative Image I).
Another sample of the ortho-sensitized litho film (which did not receive the treatment with /2-mercapto-4-pheny1- thiazole) was exposed, developed, fixed and washed in exactly the same way as just described to give a high speed high density negative image (Negative Image 11). In this instance, the film required only 20 seconds in the fixing bath to clear. The optical densities resulting from the positive and two negative images are given below:
Example XI Four and one-half moles of a ripened and washed emulsion (as described in Example III except for omission of the redispersion step) was mixed with 4 liters of a gelatin solution containing 300 g. of gelatin. After adjusting the pH to 6.0, the emulsion was redispersed by vigorous agitation for 65 minutes at 110 F. To a quantity of this redispersed emulsion containing 0.15 mole of silver halide there was added 200 ml. of water, an ethanol solution containing 0.1 g. of 4-cyclohexyl-2- mcrcaptothiazole and an acetone solution containing 3.5 mg. of a merocyanine dye of the structure:
The emulsion was then stirred for 20 minutes at 160 F., cooled to 85 F., the usual coating adjuvants added, and the emulsion was coated on the film base described in Example I.
Example XII The ripened and washed emulsion of Example XI was redispersed in a similar manner, using 83 g. of gelatin per mole of silver halide. To a portion of this emulsion containing 0.15 mole of silver halide there was added an ethanol solution containing 0.0625 g. of 2-n1ercapto-4- phenylthiazole. Preparation of the emulsion was completed and it was coated as described in Example XI.
Film strips from the coatings of Examples XI-XII were exposed through a square-root-of-two, neutral density, step wedge to an incandescent light source having a color temperature of 2800 K. and an intensity of 6000 meter-candles for 10 sec. (total exposure 60,000 m.c.s.).
After exposure the strips were bathed for 20-30 sec. at 20 C. in a solution of the following composition:
N32820:; (anhyd.) g Na SO (anhyd) g 9.8 Borax (Na B O -10H O) g 11.8 Acetic acid (glacial) ml 7.80 Potassium alum. KAl(SO -12H O g 13.1 Potassium acetate g 10 E to make 900 ml.
Adjust pH to 4.8:01 with 3 N H 80 or 3 N NaOH. H O to make 1 liter The film strips were then washed in water for minutes at 20 C., dried in air and tested by X-ray emission spectrography for silver coating weight, at various exposure levels, using a North American Philips X-ray Spectrograph Attachment Type No. 52157-A operated from an X-ray Diffraction Unit Type No. 12045. Silver coating weights were also obtained in this manner for untreated I 2 control strips of the same coatings. Results are tabulated below:
Silver Coating Weights (mg/din?) Example Processing Time, sec. Unexposed Unexposed Exposed untreated Treated 10 see.
Treated 20 40.9 22.8 0.35 XII 30 55. 5 29. 8 0. 35
Example XIII A lithographic emulsion having a silver halide composition of 30 mole percent AgBr and 70 mole percent AgCl and having 20 grams of gelatin present per mole of silver halide for the steps of precipitation and ripening was freed of unwanted, soluble, by-product salts by a coagulation and wash procedure as taught in Waller et al., US. Patent 2,489,341, wherein the silver halide and most of the gelatin were coagulated by an anionic wetting agent, sodium lauryl sulfate, using an acid coagulation environment. Following the washing step the emulsion coagulate was redispersed by adding an aqueous solution containing g. of gelatin per mole of silver halide, adjusting the pH to about 6.0 and vigorously agitating for 65 minutes at 110 F.
To a quantity of this redispersed emulsion containing 0.15 mole of silver halide there was added an ethanol solution containing 0.08 gram of 2-mercapto-4-pentylthiazole and an acetone solution containing 3.5 mg. of the merocyanine dye of Example XI. The emulsion was then stirred for 20 minutes at 160 F., cooled to F., the usual coating adjuvants added and the emulsion was coated on the film base described in Example I, at a silver coating weight of 35 mg./dm. The coating, after imagewise exposure, showed a greater rate of fixing in an aqueous solution containing 75 g. of sodium thiosulfate per liter in exposed areas than in the unexposed areas so as to form a positive silver halide image.
Example XIV Example XIII was essentially repeated except the ethanol solution containing 0.08 gram of 2-mercapto-4- pentylthiazole was replaced with an ethanol solution of another Z-mercapto-4-substituted thiazole in the quantity indicated in the table below. Also, the amount of gelatin per mole of silver halide added at redispersion varied as indicated in the table:
Wt. 01 mercnp- Added Example tan per 0.15 Thiazole substituent gelatin mole of silver at No. 4 position per mole halide, g.
0.07 Il'eptyl 84 0.09 Undeeyl- 84 0.07 Isobutyl 0.12 Alpha-naphthyl... 110 0. 12 p-Bromopnenyl. 110 0. 12 p-Nitrophenyl- 110 0.09 p-Diphenyl 84 Positive images were obtained from all coatings when tested as in Example XIII.
Example XV Example XIII was essentially repeated except the ethanol solution containing 0.08 gram of 2-mercapto-4-penty1- thiazole was replaced with ml. of an aqueous solution of the sodium salt of 2-mercapto-4-phenylthiazole, prepared by dissolving 0.3 gram of 2-mercapto-4-phenyl thiazole in 2 ml. of l-molar sodium hydroxide and diluting with water to a volume of 600 ml. Also, the amount of gelatin per mole of silver halide added at redispersion was 47 grams rather than 80 grams. When tested as in Example XIII, the results were similar, a positive image being obtained from this coating.
The 2-mercapto-4-pentyl-, heptyl, undecyl, etc. thiazole compounds can be prepared by procedures like those for making lower homologues and analogues. Thus, they can be made by the procedures of Ritter et al., J. Am. Chem. Soc., vol. 70, pp. 3419-21, from NH CSSNH and the appropriate N-alkyl chloromethyl ketone, etc.
When the sodium, potassium or ammonium salt is used in place of the free mercaptan, there are advantages as these salts can be added from aqueous solution instead of from an ethanol solution.
The silver halide photosoluble elements of this invention differ from conventional silver halide emulsions containing antifogging agents in that the insolubilizing compounds used in the photosoluble elements are present in substantially greater than fog-inhibiting amounts, the latter amounts being the maximum quantity which provides low fog without serious loss in speed and photographic quality. For this reason it is not practical to use photosoluble elements in place of ordinary silver halide photograpmc materials. When photosoluble elements are exposed and processed normally, development proceeds slowly and incompletely to give a negative silver image having much less speed and lower density. In addition, 1 .ing is slower and may be incomplete for practical fixing times. Thus, photosoluble elements require longer conventional processing times and give slower speed, inferior quality images when compared to ordinary silver halide photographic elements.
The novel photographic products of this invention have numerous advantages. A primary advantage is the simplicity of their preparation. They can be exposed and processed to images under ordinary room light conditions.
The photographic processes applicable to the new products of the invention likewise have advantages over previously known systems based on selective reduction of exposed silver halide for forming either direct positive or negative images Without resorting to the special effects and sensitizing procedures previously used for preparing such images. in addition, since image formation does not re quire selective reduction, this present process is not limited to the use of certain photographic developing agents but may be accomplished by using a wide range of reducing agents. Many such compounds are of very low cost and can be used to form images of much higher covering power than customary, thus elfecting important economies in processing, as well as greatly increasing the efiiciency of the silver image with a resultant increase in sensitivity.
Another advantage of this invention is that it provides new elements for forming silver images that do not require special equipment but instead can be used with conventional equipment and apparatus. A further advantage is that the elements can be used successfully by photographic technicians and photographers of ordinary skill. A still further advantage is that the elements can be processed with conventional reducing agents, e.g., developers and fixing agents. A still further advantage is that the new elements can be used to produce images without selective reduction.
I claim:
1. A photographic silver halide emulsion layer wherein any heavy metal salt present is a silver halide comprising, before exposure to actinic radiation, light-sensitive silver halide crystals having associated therewith in substantially greater than fog-inhibiting amounts a silver mercaptide of a mercapto compound of the formula:
where R is a hydrocarbon nucleus of 4-12 carbon atoms, said silver mercaptide being of lower solubility in Water than silver chloride and the silver halide crystals so associated with the silver mercaptide dissolving more slowly in aqueous sodium thiosulfate than untreated silver halide crystals at a predetermined pH, the mercapto compound forming the mercaptide being present in such an amount, in terms of the ratio of its Weight to the surface area of said silver halide crystals, that when admixed in such ratio with an aqueous silver chlorobromide (70/30 mole percent) gelatin dispersion containing 57 g. of gelatin per mole Ag and .57 mg. of Ag per ml., and said silver chlorobromide dispersion is treated with 10%, by weight, aqueous sodium thiosulfate (so that the resulting mixture contains 0.29 mg. of silver and mg. of sodium thiosulfate), at least three times the amount of silver chlorobromide remains undissolved as in a similar dispersion successively treated with 5%, by weight, aqueous sodium hypochlorite and 10%, by Weight, aqueous sodium thiosulfate (so that the resulting mixture contains 0.29 mg. of silver, 25 mg. of sodium hypochlorite and 100 mg. of sodium thiosulfate), after vigorous agitation of the dispersions for 30 seconds at 25 C.
2. An emulsion layer according to claim 1 wherein said emulsion layer contains gelatin as the binding agent for the crystals.
3. An emulsion layer according to claim 1 wherein the silver halide is silver chlorobromide.
4. A photographic silver halide emulsion layer wherein any heavy metal salt present is a silver halide comprising, before exposure to actinic radiation, light-sensitive silver halide crystals having associated therewith in substantially greater than fog-inhibiting amounts a silver mercaptide of a mercapto compound of the formula:
Where R is an unsubstituted hydrocarbon radical of 6-10 carbon atoms having a cyclic hydrocarbon radical of six carbon atoms attached through a cyclic carbon atom thereof to the 4-carbon atom of the thiazole ring, said silver mercaptide being of lower solubility in water than silver chloride and less soluble in 10% aqueous sodium thiosulfate than untreated silver halide crystals at a predeter-' mined pH, said mercapto compound forming the mercap tide being present in such an amount, in terms of the ratio of its weight to the surface area of said silver halide crystals, that when admixed in such ratio with an aqueous silver chlorobromide (70/30 mole percent) gelatin dis persion containing 57 g. of gelatin per mole Ag and .57 mg. of Ag/ml. and said silver chlorobromide dispersion is treated with 10%, by Weight, aqueous sodium thiosulfate (so that the resulting mixture contains 0.29 mg. of silver and 100 mg. of sodium thiosulfate), at least three times the amount of silver chlorobromide remains undissolved as in a similar dispersion successively treated with 5%, by weight, aqueous sodium hypochlorite and 10%, by weight, aqueous sodium thiosulfate (so that the resulting mixture contains 0.29 mg. of silver, 25 mg. of sodium hypochlorite and 100 mg. of sodium thiosulfate), after vigorous agitation of the dispersions for 30 seconds at 25 C.
5. An emulsion layer according to claim 4 wherein R is phenyl.
6. An emulsion layer according to claim 4 wherein R is phenyl, the silver halide is silver chlorobromide and gelatin is present as the binding agent for the silver chlorobromide.
7. An emulsion layer according to claim 4 wherein R is cyclohexyl.
8. An emulsion layer according to claim 4 wherein R is cyclohexyl, the silver halide is silver chlorobromide and gelatin is present as the binding agent for the silver chlorobromide.
9. A photographic silver halide emulsion layer wherein any heavy metal salt present is a silver halide comprising, before exposure to actinic radiation, light-sensitive silver halide crystals having associated therewith in substantially greater than fog-inhibiting amounts a silver mercaptide of a mercapto compound, said silver mercaptide and its concentration relative to the surface area of the silver halide is characterized in that when tested in a gelatino-silver chlorobromide emulsion (70% silver chloride and 30% silver bromide) which is (a) applied to a photographic film base at a coating weight of 100 mg./dm. of silver halide and 100 mg./dm. of gelatin,
(b) given an exposure of no more than 60,000 meter candle-seconds to a light of a color temperature of 2800 K.,
(c) bathed for 30 seconds at C. in the following solution:
Na S O (anhyd.) g 100 Na SO (anhyd.) g 9.8 Borax (Na B O 10H O) g 11.8 Acetic acid (glacial) ml 7.8 Potassium alum, KAl(SO -12H O g 13.1 Potassium acetate g 10.0
H 10 to make 900 ml. Adjust pH to 4.8i0.1 with 3 N H 80 or 3 N NaOH. H O to make 1 liter and (d) washed in water for 5 minutes at 20 C. and
dried in air, at least mg./dm. of silver halide remains in the unexposed areas while no more than 1 n1g./drn. of silver halide remains in the area having been given said exposure. 10. A photographic silver halide composition wherein any heavy metal salt is a silver halide comprising, before exposure to actinic radiation, light-sensitive silver halide crystals having associated therewith in substantially greater than fog-inhibiting amounts a silver mercaptide of a mercapto compound of the formula:
II It HC o-srr where R is a hydrocarbon nucleus of 4-12 carbon atoms, said silver mercaptide being of lower solubility in water than silver chloride and the silver halide crystals so associated with the silver mercaptide dissolving more slowly in 10% aqueous sodium thiosulfate than untreated silver halide crystals at a predetermined pH, the mercapto compound forming the mercaptide being present in such an amount, in terms of the ratio of its Weight to the surface area of said silver halide crystals, that when admixed in such ratio with an aqueous silver chlorobromide (70/ mole percent) gelatin dispersion containing 57 g. of gelatin per mole Ag and .57 mg. of Ag per ml., and said silver chlorobromide dispersion is treated with 10%, by weight, aqueous sodium thiosulfate (so that the resulting mixture contains 0.29 mg. of silver and 100 mg. of sodium thiosulfate), at least three times the amount of silver chlorobromide remains undissolved as in a similar dis persion successively treated with 5%, by weight, aqueous sodium hypochlorite and 10% by weight, aqueous sodium thiosulfate (so that the resulting mixture contains 0.29 mg. of silver, 25 mg. of sodium hypochlorite and 100 mg. of sodium thiosulfate), after vigorous agitation of the dispersions for 30 seconds at 25 C.
11. A photographic silver halide emulsion layer comprising, before exposure to actinic radiation, light-sensitive silver halide crystals having associated therewith in substantially greater than fog-inhibiting amounts, and from one-half the amount required to just cover the surface of a mole of the silver halide crystals to 0.75 gram per mole of said crystals of 2-mercapto-4-phenylthiazole, said compound thereby being present in such an amount, in terms of the ratio of its Weight to the surface area of said silver halide crystals, that when admixed in such ratio with an aqueous silver chlorobromide 30 mole percent) gelatin dispersion containing 57 g. of gelatin per mole Ag and .57 mg. of Ag per ml., and said silver chlorobromide dispersion is treated with 10%, by weight, aqueous sodium thiosulfate (so that the resulting mixture contains 0.29 mg. of silver and mg. of sodium thiosulfate), at least three times the amount of silver chlorobromide remains undissolved as in a similar dispersion successively treated with 5%, by weight, aqueous sodium hypochlorite and 10%, by weight, aqueous sodium thiosulfate (so that the resulting mixture contains 0.29 mg. of silver, 25 mg. of sodium hypochlorite and 100 mg. of sodium thiosulfate), after vigorous agitation of the dispersions for 30 seconds at 25 C.
12. An emulsion layer according to claim 11 wherein the silver halide is silver chlorobromide and gelatin is present as the binding agent for the silver chlorobromide.
References Cited by the Examiner Mees: The Theory of the Photographic Process"; Macmillan, 1942, pages 306-309 of interest.
Faerman et al.: The Photographic Action of 2-Mercapto Benzoxazide, Uspekhi Nauchonoi Fotografii, Akademiya Nauk, S.S.S.R., Otdelenie Khimicheskikh Nauk 5, 107-113 (1957).
Van Veelen et al.: Phot. Korr. 99, No. 9, September 1963, pages 139-145 of interest.
NORMAN G. TORCHIN, Primary Examiner.

Claims (1)

1. A PHOTOGRAPHIC SILVER HALIDE EMULSION LAYER WHEREIN ANY HEAVY METAL SALT PRESENT IS A SILVER HALIDE COMPRISING, BEFORE EXPOSURE TO ACTINIC RADIATION, LIGHT-SENSITIVE SILVER HALIDE CRYSTALS HAVING ASSOCIATED THEREWITH IN SUBSTANTIALLY GREATER THAN FOG-INHIBITING AMOUNTS A SILVER MERCAPTIDE OF A MERCAPTO COMPOUND OF THE FORMULA:
US317824A 1961-12-08 1963-10-21 Photographic compositions, layers and elements Expired - Lifetime US3155519A (en)

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US236418A US3155516A (en) 1961-12-08 1962-11-08 Photographic products
US236417A US3155515A (en) 1961-12-08 1962-11-08 Photographic products
US236420A US3155507A (en) 1961-12-08 1962-11-08 Photographic processes
US236412A US3155514A (en) 1961-12-08 1962-11-08 Photographic compositions and elements
DEP30723A DE1226877B (en) 1961-12-08 1962-12-07 Silver halide photographic emulsion
GB46345/62A GB1031903A (en) 1961-12-08 1962-12-07 Photographic silver halide materials and processes
GB46344/62A GB1031902A (en) 1961-12-08 1962-12-07 Improvements in silver halide photography
DEP30721A DE1261397B (en) 1961-12-08 1962-12-07 Photographic process for producing positive images
US317824A US3155519A (en) 1961-12-08 1963-10-21 Photographic compositions, layers and elements
NL6408533A NL6408533A (en) 1961-12-08 1964-07-24
US388919A US3418124A (en) 1961-12-08 1964-08-11 High contrast direct positive by using active cations in silver halide solvent
DK395464A DK119392B (en) 1961-12-08 1964-08-11 Photographic silver halide material for copying.
BE651688A BE651688A (en) 1961-12-08 1964-08-11
US390460A US3384485A (en) 1961-12-08 1964-08-18 Silver halide emulsions photosolubilized with optical sensitizing dyes and silver mercaptides
CH1270464A CH486719A (en) 1961-12-08 1964-09-30 Halogen silver photographic emulsion and its uses
US403661A US3284206A (en) 1961-12-08 1964-10-13 Image yielding layers
GB34231/65A GB1111226A (en) 1961-12-08 1965-08-10 Improvements relating to the production of images
DEP37430A DE1294186B (en) 1961-12-08 1965-08-10 Photographic process for producing positive images
BE668111D BE668111A (en) 1961-12-08 1965-08-10
DEP37479A DE1293581B (en) 1961-12-08 1965-08-18 Silver halide photographic emulsion
BE670823D BE670823A (en) 1961-12-08 1965-10-12
GB43289/65A GB1124772A (en) 1961-12-08 1965-10-12 Improvements in silver halide photography
DEP37856A DE1293582B (en) 1961-12-08 1965-10-13 Silver halide photographic emulsion

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US236417A US3155515A (en) 1961-12-08 1962-11-08 Photographic products
US236418A US3155516A (en) 1961-12-08 1962-11-08 Photographic products
US317824A US3155519A (en) 1961-12-08 1963-10-21 Photographic compositions, layers and elements
NL6408533A NL6408533A (en) 1961-12-08 1964-07-24
US388919A US3418124A (en) 1961-12-08 1964-08-11 High contrast direct positive by using active cations in silver halide solvent
US390460A US3384485A (en) 1961-12-08 1964-08-18 Silver halide emulsions photosolubilized with optical sensitizing dyes and silver mercaptides
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US3647439A (en) * 1968-10-01 1972-03-07 Eastman Kodak Co Photographic element, composition and process
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US3155507A (en) 1964-11-03
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US3155516A (en) 1964-11-03
US3155515A (en) 1964-11-03
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FR89467E (en)
DE1261397B (en) 1968-02-15

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