US3655390A - Direct positive emulsions containing amine boranes and bismuth salts - Google Patents

Direct positive emulsions containing amine boranes and bismuth salts Download PDF

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Publication number
US3655390A
US3655390A US861501A US3655390DA US3655390A US 3655390 A US3655390 A US 3655390A US 861501 A US861501 A US 861501A US 3655390D A US3655390D A US 3655390DA US 3655390 A US3655390 A US 3655390A
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emulsion
borane
bismuth
direct positive
emulsion according
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US861501A
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Joseph De Witt Overman
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EIDP Inc
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EI Du Pont de Nemours and 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
    • G03C1/485—Direct positive emulsions
    • G03C1/48515—Direct positive emulsions prefogged

Definitions

  • ABSTRACT Direct positive photographic silver halide emulsion layers containing about 0.00033 gram to 12.0 grams of an amine borane per mole of silver halide, and about 1.5 X 10 to 1.2 X 10 moles of a salt of bismuth per 1.5 moles of silver nitrate used to prepare the silver halide.
  • This invention relates to radiation-sensitive photographic materials, and more particularly to radiation-sensitive silver halide developing-out emulsions, and elements coated with such emulsions. Still more particularly, this invention relates to radiation-sensitive silver halide developing emulsions of the direct positive type. This invention, in addition, relates to processes for producing direct positive images utilizing the above emulsions.
  • Developing-out photographic emulsions are classified broadly into two types, namely (1 those which, when exposed and developed produce negative images of the originals and (2) those which when exposed and developed, produce positive images of the originals. This invention is concerned with this latter type.
  • Direct positive images may be produced in a variety of ways using silver halide emulsions.
  • a silver halide emulsion may be given a short, over-all exposure to high intensity radiation and then given a longer imagewise exposure to radiation of lower intensity.
  • Another method is to expose imagewise and develop and then flash expose and redevelop.
  • a still further method is to chemically fog the silver halide grains with, for example, formaldehyde, hydrazine, sodium arsenite, silver ions and other nonsulfide fogging agents, instead of using a solarizing exposure.
  • a positive image is obtained.
  • a desensitizing compound usually a colored desensitizing dye.
  • 3,445,235 teaches the use of rhodium and iridium salts to prevent desensitization marks caused by kinking.
  • the susceptibility toward kinking has never been troublesome in the prior art direct positive emulsion layers. This has probably been because of their very low sensitivity and slow speed.
  • kinking has become a problem and manifests itself by the fact that kinked areas bleach faster than nonkinked areas during exposure.
  • an improved high speed direct positive emulsion layer can be obtained by incorporating one or more amine borane compounds as fogging agents and a water-soluble salt of bismuth as a speed improver and antikinking agent in the silver halide emulsion.
  • the emulsion preferably is a gelatino-silver chlorobromide emulsion containing from about to percent by weight of silver bromide and optionally may contain, in addition to the two halides, from 0 to 6 percent by weight of silver iodide.
  • One, two, or more bismuth salts are used in amounts of from 1.5 X10 to 1.7 X 10 mole per 1.5 moles of silver nitrate and preferably are added during the precipitation phase of making the emulsion.
  • the optimum concentration of bismuth salt can be determined by observing the density changes in a kinked area when the element is given the customary bleaching light exposure as compared to unkinked areas and when the optimum speed is reached. High levels of the bismuth salts may cause an undesirable reduction in maximum densities.
  • the method of kinking for test purposes involves merely bending a strip of film through an angle of about 90 over a small radius of curvature before exposure and determining the ratio of minimum net density in a kinked area to the net density in the nonkinked area.
  • Suitable water-soluble bismuth salts include bismuth nitrate, bismuth trichloride, bismuth citrate, bismuth sulfate and bismuth tartrate.
  • the borane fogging agents may be added to the emulsions in amounts ranging from 0.00033 grams to 12.0 grams per mole of silver halide and preferably from 0.013 to 1.3 grams per mole of silver halide. They may be added either as a solid or dissolved in a suitable solvent.
  • the effectiveness of the borane compounds in fogging a silver halide emulsion is influenced by the pH of the system, the higher the pH, the greater the fogging for a given amount of borane compound. Of course, certain of the borane compounds are more effective than others when used in equivalent quantities, The fogging effect produced by the borane compounds is bleachable by light exposure prior to development.
  • a suitable developer may be any conventional alkaline, photographic developing solution which would be used for standard processing of the above direct positive emulsions in the absence of the amine borane compounds.
  • the mechanism is not clearly understood, the light bleaching effect is believed due to solarization.
  • soluble bismuth salts such as bismuth trichloride and bismuth nitrate prevent more rapid bleaching in kinked areas and still do not affect unkinked areas and tend to increase the speed and give lower minimum densities in direct positive emulsions.
  • the amine borane compounds will act to chemically fog all types of emulsion, the solarizing effect appears to be more efficient in silver chlorobromide emulsions.
  • amine borane compounds which have been found useful as chemical fogging compounds in this invention are the following:
  • Alkylamine boranes Typical of these amine boranes are those of the formula where R; is an alkyl radical of 12() carbon atoms, and R2 and R; are H or alkyl of 1-20 carbon atoms. Examples of such boranes are r 1. Trlmethylamine borane, CH N:BH
  • B, -y-picol1ne borane is a mixture of a-picoline borane, fl-picoline DESCRIPTION OF THE PREFERRED EMBODIMENTS
  • the chemical fogging agents of this invention be added to the silver halide emulsion after it has been made, ripened, and washed to remove the excess soluble salts resulting from the precipitation of the silver halides.
  • the borane compounds are added just prior to or during the digestion between pH 5 and 7 and maintained at this level during digestion. After digestion, the conventional coating aids are added. The emulsion is then coated and dried in the manner known to those skilled in photographic manufacturing methods.
  • sensitometric characteristics of the direct positive emulsions may be determined by processing test strips of the coated layers in the following manner.
  • a test strip in each of the following examples is fixed out in a conventional photographic fixer to provide a means of establishing the minimum density (D Test strips are exposed in an intensity scale sensitometer (described on page 616, Mees, The Theory of the Photographic Process, Mac Millan Company, New York, 1942) using a 2 step wedge and log exposure 5.92.
  • the exposed strip is developed for 1% minutes at 68 F. in a a developer having the composition:
  • the minimum density (D equals the lowest density above that of the fixed out strip mentioned above.
  • the maximum density is the highest density above D,,.;,,.
  • the speed of a typical commercial direct positive in terms of lO0/E X 10' is 10.3 and the conventional material has a D of 0.02 and a D,,,,,, of 3.5.
  • the resulting emulsions were then cooled, washed and redispersed in the manner disclosed in Moede, US. Pat. No. 2,772,165 issued Nov. 27, 1956.
  • the temperature of the redispersed emulsion was raised to F. and there was then added to each 87 grams of gelatin, and the pH was adjusted to 5.7.
  • the usual coating aids including a gelatin hardener were added and the emulsions were each coated on a photographic film support and dried in the con ventional manner.
  • Kink sensitivity 1 (Ratio of min. density in klnked Moles Blper areas to density 1 Ideally the kink sensitivity should be equal to one.
  • Example 11 was repeated except that there was added to each emulsion 160 milligrams of trimethylamine borane per 1.5 moles of silver nitrate. Sensitometric evaluation gave the following data:
  • Example 11 was repeated except that there was added to each emulsion 8 milligrams of morpholine borane per 1.5 moles of silver nitrate.
  • the sensitometric results were as follows:
  • Example 11 was repeated except that 1.6 grams of potassium iodide and 8 milligrams of morpholine borane per 1.5 moles of silver nitrate was added to each emulsion.
  • the amount of bismuth nitrate is shown in the following table along with the sensitometric data:
  • emulsion coated elements of the preferred composition of the above examples good duplicates can be made by contact printing, using either carbon arc lamps or tungsten photofiood lamps as a light source.
  • the emulsion coated element may be used for reproducing continuous tone negatives,
  • the photographic elements of this invention provide direct positive images having extremely low minimum densities and high maximum densities and are extremely fast as compared to the direct positive elements of the prior art and at the same time are free of kink desensitization.
  • the elements of this invention may be developed in any standard developing solution using standard technique. Variations in the developing solution will have much the same effect as they would in developing nonreversal emulsions. No pre-exposure operations or auxiliary processing procedures are necessary or desirable in using the novel elements of this invention. It is also unnecessary to utilize stain producing densitizing dyes or other desensitizing compounds in the emulsion.
  • the boranes as chemical fogging agents are far superior to formaldehyde, the principal fogging agent of the prior art, because the borane compounds do not have any hardening effect on the gelatin layer. This affords a method of providing wash-off relief direct positives by using a hardening developer.
  • the emulsions of this invention may be coated on any suitable base including paper and transparent film supports.
  • the cellulosic supports e.g., cellulose acetate, cellulose triacetate, cellulose mixed ester, etc.
  • Polymerized vinyl compounds e.g., copolymerized vinyl acetate and vinyl chloride, polystyrene, and polymerized acrylates may also be mentioned.
  • the film can be any polyester film made according to the teachings of Alles, U.S. Pat. No. 2,779,684 and the patents referred to in the specification of that patent.
  • Other suitable supports are the polyethylene terephthalate/isophthalates of British Pat. No. 766,290 and Canadian Pat. No.
  • emulsion according to claim 1 wherein the emulsion is a gelatino-silver chlorobromide emulsion containing 80 to 90 percent by weight of silver bromide.
  • amine borane compound is an alkylamine borane of the formula where R is an alkyl radical of one-20 carbon atoms, and R and R are H or alkyl of one-20 carbon atoms.
  • a photographic element comprising a sheet support bearing a layer of an emulsion as defined in claim I.

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  • Chemical & Material Sciences (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)
US861501A 1969-09-26 1969-09-26 Direct positive emulsions containing amine boranes and bismuth salts Expired - Lifetime US3655390A (en)

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3804632A (en) * 1972-02-15 1974-04-16 Du Pont Metalloboranes as fogging agents in direct positive emulsions
US3852071A (en) * 1971-11-09 1974-12-03 Fuji Photo Film Co Ltd Process of producing positive images
US4826758A (en) * 1986-04-19 1989-05-02 Konishiroku Photo Industry Co., Ltd. Silver halide emulsion and process for preparing it, and light-sensitive halide photographic material employing said silver halide emulsion
US5411855A (en) * 1993-12-16 1995-05-02 Eastman Kodak Company Photographic element exhibiting improved speed and stability
US20040016643A1 (en) * 2001-03-02 2004-01-29 Emmonds Donald D. Process for electrocoating metal blanks and coiled metal substrates
US20040253552A1 (en) * 2003-06-12 2004-12-16 Roberts Michael R. High-speed positive-working photothermographic system comprising an accelerating agent
US20040259041A1 (en) * 2003-06-12 2004-12-23 Roberts Michael R. High-speed positive-working photothermographic system

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3361564A (en) * 1964-08-27 1968-01-02 Du Pont Amine borane as fogging agent in direct positive
US3418122A (en) * 1965-08-23 1968-12-24 Eastman Kodak Co Photodevelopment of silver halide print-out material
US3445235A (en) * 1965-07-15 1969-05-20 Du Pont Rhodium and iridium salts as anti-kinking agent in direct positive silver halide emulsions
US3447927A (en) * 1965-07-13 1969-06-03 Eastman Kodak Co Print-out silver halide emulsions capable of being chemically developed and/or photodeveloped
US3451819A (en) * 1965-08-09 1969-06-24 Du Pont Photosoluble silver halide emulsion made spontaneously developable with amine boranes
US3508925A (en) * 1967-09-08 1970-04-28 Eastman Kodak Co Method for preparing gelatino emulsions containing latexes and polyvalent salts and products obtained thereby

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3361564A (en) * 1964-08-27 1968-01-02 Du Pont Amine borane as fogging agent in direct positive
US3447927A (en) * 1965-07-13 1969-06-03 Eastman Kodak Co Print-out silver halide emulsions capable of being chemically developed and/or photodeveloped
US3445235A (en) * 1965-07-15 1969-05-20 Du Pont Rhodium and iridium salts as anti-kinking agent in direct positive silver halide emulsions
US3451819A (en) * 1965-08-09 1969-06-24 Du Pont Photosoluble silver halide emulsion made spontaneously developable with amine boranes
US3418122A (en) * 1965-08-23 1968-12-24 Eastman Kodak Co Photodevelopment of silver halide print-out material
US3508925A (en) * 1967-09-08 1970-04-28 Eastman Kodak Co Method for preparing gelatino emulsions containing latexes and polyvalent salts and products obtained thereby

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3852071A (en) * 1971-11-09 1974-12-03 Fuji Photo Film Co Ltd Process of producing positive images
US3804632A (en) * 1972-02-15 1974-04-16 Du Pont Metalloboranes as fogging agents in direct positive emulsions
US4826758A (en) * 1986-04-19 1989-05-02 Konishiroku Photo Industry Co., Ltd. Silver halide emulsion and process for preparing it, and light-sensitive halide photographic material employing said silver halide emulsion
US5411855A (en) * 1993-12-16 1995-05-02 Eastman Kodak Company Photographic element exhibiting improved speed and stability
US20040016643A1 (en) * 2001-03-02 2004-01-29 Emmonds Donald D. Process for electrocoating metal blanks and coiled metal substrates
US20040253552A1 (en) * 2003-06-12 2004-12-16 Roberts Michael R. High-speed positive-working photothermographic system comprising an accelerating agent
US20040259041A1 (en) * 2003-06-12 2004-12-23 Roberts Michael R. High-speed positive-working photothermographic system
US7183024B2 (en) 2003-06-12 2007-02-27 Eastman Kodak Company High-speed positive-working photothermographic system
US7198889B2 (en) 2003-06-12 2007-04-03 Eastman Kodak Company High-speed positive-working photothermographic system comprising an accelerating agent

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