US3650758A - Direct-positive print-out silver halide emulsion fogged to visible density - Google Patents

Direct-positive print-out silver halide emulsion fogged to visible density Download PDF

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Publication number
US3650758A
US3650758A US56703A US3650758DA US3650758A US 3650758 A US3650758 A US 3650758A US 56703 A US56703 A US 56703A US 3650758D A US3650758D A US 3650758DA US 3650758 A US3650758 A US 3650758A
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Prior art keywords
emulsion
electron
positive
direct
silver halide
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US56703A
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Paul Brewster Gilman Jr
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Eastman Kodak Co
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Eastman Kodak Co
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
    • G03C1/485—Direct positive emulsions
    • G03C1/48515—Direct positive emulsions prefogged
    • G03C1/48523—Direct positive emulsions prefogged characterised by the desensitiser

Definitions

  • ABSTRACT Print-out, direct-positive images are obtained by exposure of a silver bromide emulsion which has been uniformly fogged to a visible density and contains an electron-accepting compound.
  • lt is a further object to provide such materials and methods which are capable of forming this direct-positive print-out image at exposure levels normally used to form negative images in print-out materials.
  • the method in general, comprises fogging to a visible density, e.g., from 0.30 to 2.0, and preferably from 0.50 to 1.5, a bulk silver halide emulsion wherein at least 50 mole percent of the halide of said silver halide is bromide.
  • An electron-acceptor compound which has a reduction potential less negative than minus 1.0 and an oxidation potential more positive than plus 0.4 is added to the visibly fogged emulsion in the dark, preferably with agitation and while said emulsion is in the bulk state.
  • the resulting emulsion can then be coated on a suitable paper or film support to obtain the novel photographic element of the invention comprising a support coated with a silver halide emulsion of which the silver halide content is at least 50 mole percent bromide, the emulsion being visible fogged prior to image exposure to a density of at least 0.3 and containing an electron-acceptor compound which has a reduction potential less negative than minus 1.0 and an oxidation potential more positive than plus 0.4.
  • the silver halide emulsions which can be fogged and used in combination with the electron acceptors according to this invention to provide direct-positive print-out emulsions generally include silver bromide, silver bromoiodide, silver chlorobromoiodide and the like or mixtures thereof.
  • the halide of the silver halide is at least 50 mole percent bromide.
  • the halide of the silver halide contains less than mole percent iodide.
  • the emulsions may be coarse-grain or fine-grain emulsions and can be prepared by any of the procedures used for making silver halide emulsions, e.g., single-jet procedures, double-jet procedures, procedures using ammoniacal, thiocyanate and/or thioether ripening agents and the like.
  • the fogging of the silver halide to a visible density of at least 0.3 is accomplished by light fogging the bulk silver halide emulsion while agitating it.
  • Light fogging is used herein in its broad sense to include exposure to any visible or invisible electromagnetic radiation that will fog the silver halide. This will normally be radiation in the range of intrinsic sensitivity of silver halides which is in the ultraviolet to blue range of the spectrum.
  • emulsions which contain addenda which do not adversely affect the ultimate production of a direct-positive print-out image.
  • the silver halide is agitated during the fogging exposure.
  • the reason for this is to achieve uniform fogging of the silver halide grains.
  • Any of the normal means for stirring and agitating silver halide emulsions during formulation can be employed.
  • intensity of illumination and duration of exposure can be employed which will achieve the desired visible density and uniformity of fogging.
  • exposure is equal to intensity multiplied by time, one can employ a high intensity for a relatively short time or a lower intensity for a longer time.
  • Various sources of the desired radiation can be employed, including daylight, but normally it is more convenient to use some type of artificial illumination such as incandescent tungsten lamps arranged to give maximum exposure, e.g., including use of a transparent mixing vessel for the emulsion.
  • some type of artificial illumination such as incandescent tungsten lamps arranged to give maximum exposure, e.g., including use of a transparent mixing vessel for the emulsion.
  • Light fogging offers important advantages in achieving the desired visible density in the fogging stage of my method. For instance, the fog produced by light fogging of the grains bleaches readily in the subsequent imagewise exposure of the photographic elements in the presence of electron acceptors.
  • the fogging step preferably consists of radiation exposure of about 300 to 800 nm.
  • the direct-positive printout emulsions of this invention can be made in certain embodiments with a combination of light fogging with chemical fogging, and the expression light fogging" is used herein to include light fogging alone or a combination of light and chemical fogging.
  • the silver halide can be chemically fogged, for example, with a reducing agent such as thiourea dioxide, hydrazine compounds or stannous chloride or with a combination of such a reducing agent and a compound of a noble metal such as gold, as disclosed, for example, in British Pat. No. 723,019.
  • the bulk silver halide, as in light fogging is agitated during such reduction in order to insure uniformity of visible fogging.
  • the electron-acceptor compounds useful herein are organic compounds which can be termed desensitizing electron acceptors and have been referred to in the art as desensitizers for negative silver halide emulsions. They can be characterized by their polarographic half wave potentials, i.e., their oxidationreduction potentials as determined by polarography. Thus, they are organic compounds having a reduction potential less negative thari'minus 1.0 and an oxidation potential more positive than plus 0.4.
  • cathodic measurements can be made with a l X 10 molar solution of the electron acceptor in a solvent, for example, methanol which is 0.05 molar in lithium chloride using a dropping mercury electrode, with the polarographic half wave potential for the most positive cathodic wave being measured.
  • Anodic measurements can be made with l X 10 molar aqueous solvent solutions, for example, methanolic solutions of the electron acceptor which are 0.05 molar in sodium acetate and 0.005 molar in acetic acid using a carbon paste of pyrolytic graphite electrode, with the voltametric half peak potential for the most negative anodic response being measured.
  • the reference electrode can be an aqueous silver chloride (saturated potassium chloride) electrode at 20 C.
  • Electrochemical measurements of this type are known in the art and are described, for example, in New instrumental Methods in Eiectrochemistry, by Delahay, Interscience Publishers, New York, N.Y., 1954; Polarography, by Kolthoff et al., 2nd Edit. lnterscience Publishers, New York, N.Y., 1952; Anal. Chem., 36, 2,426 (1964), by Elving; and Anal. Chem., 30, 1,576 (1958), by Adams. Plus and minus signs are according to lUPAC, Sweden Convention, 1953.
  • the significance of these limits for the oxidation-reduction potentials of the electron-acceptor compounds is that if the oxidation potential is less positive than plus 0.4, the compound will not be capable of oxidizing and thereby bleaching surface fog of the silver halide upon imagewise exposure. If the reduction potential is more negative than minus 1.0, the compound will increase rather than decrease the density of the prefogged emulsion, i.e., by photoreduction of silver halide.
  • the electron-accepting compounds or desensitizers are used in the emulsions of this invention in a desensitizing concentration, i.e., a concentration which would provide at least a 0.3 log E decrease in blue-speed sensitivity of a sulfur and gold surface-sensitized silver bromoiodide (6 mole percent iodide) emulsion when developed at 25 C. in a surface developer such as Kodak D-19.
  • a desensitizing concentration i.e., a concentration which would provide at least a 0.3 log E decrease in blue-speed sensitivity ofa sulfur and gold surface-sensitized silver bromoiodide (6 mole percent iodide) emulsion when developed at 25 C. in a surface developer such as Kodak D-19.
  • the electron-accepting desensitizing compounds can be selected from a wide range of such compounds which have the required oxidation and reduction potentials, including various photoelectron-accepting compounds or desensitizing dyes used in photographic reversal systems.
  • Compounds of this type include the known desensitizers which trap electrons as disclosed in British Pat. No. 723,019.
  • spectral-sensitizing electron acceptors such as disclosed in U.S. Pat. Nos. 3,501,305 and 3,501,310.
  • Still another suitable class of electron-acceptor compounds from which those of the required oxidation and reduction potentials can be selected include bipyridinium salts which have two pyridinium nucleijoined by a linkage attached to a carbon atom of each of the nuclei.
  • the two pyridinium nuclei can be joined by any suitable linkage such as a single covalent bond, a vinylene linkage or an alkylene linkage.
  • bipyridinium compounds are disclosed in Gilman, US. Pat. application, Ser. No. 776,262 filed Nov. 15, 1968; Fry et al., U.S. Pat. No. 3,035,917; Fry et al., U.S. Pat. No. 3,124,458; British Pat. No. 714,290; Belgian Pat. No. 626,303; and Homer et al., J. Chem. Soc., 1960, 2,498.
  • the electron-acceptor compound is incorporated in the emulsion in a desensitizing amount, that is to say, an amount efficient to prevent latent negative image formation during the image-exposure step.
  • the electron acceptor is used to desensitize the emulsion and, therefore, enough is added so that a negative image is not formed when the prefogged emulsion is exposed imagewise.
  • the specific concentration which gives best results for each combination of variables, e.g., the particular emulsion and desensitizing compound, can be determined by routine testing, but will normally lie in the range from about 10 to 1000 mg. per mole of silver halide.
  • the electron acceptor is added to the silver halide emulsion in a desensitizing amount by any of the known emulsion formulating techniques. Thereafter, the emulsion is coated on a support to form a photographic element at a coverage, for example, of about 50 to 500 mg. of silver per square foot of support.
  • Example 1 The following examples of the preparation of photographic elements provide a further understanding of this invention.
  • Example 1 The following examples of the preparation of photographic elements provide a further understanding of this invention.
  • a silver bromide emulsion (1.72 kg. of emulsion contains 1 mole of silver and 80 g. of gel). This melted emulsion, while being agitated, is then exposed to a l00-watt tungsten bulb for 10 minutes at a distance of 12 inches, at which time it reaches a visible density when coated of about 0.5.
  • Print-out wedge spectrograms made on the coating containing 1 milliliter of phenosafranine dye solution to ml. of emulsion show two peaks, one from 350 to 450 m. and another which extends from 550 to 620 m., indicating that the silver is being bleached by the action of light absorbed both by the silver bromide and the phenosafranine dye.
  • a directpositive print-out element with satisfactory speed and contrast is provided. They demonstrate an important advantage of the novel photographic elements of providing a direct-positive printout image having adequate stability for many purposes without the necessity of chemical treatment after image-wise exposure. It should be understood, however, that if the electron acceptor is not removed from the element after exposure to an image, the maximum density of the image will gradually decrease when exposed to light or other radiation. Therefore, it is sometimes desirable, in order to stabilize the image, to treat the print-out element in various ways. One suitable treatment is simply to rinse the print-out element with water to remove the electron-acceptor compound or compounds.
  • the photographic layers used in the practice of this invention may be coated by various coating procedures including dip coating, air knife coating, curtain coating or extrusion coating using hoppers of the type described in Beguin, U.S. Pat. No. 2,681,294. If desired, two or more layers may be coated simultaneously by the procedures described in Russell, U.S. Pat. No. 2,761,791, and Wynn, British Pat. No. 837,095.
  • This invention also can be used for silver halide layers coated by vacuum evaporation as described in British Pat. No. 968,453 and LuValle et al., U.S. Pat. No. 3,219,451.
  • Typical supports include cellulose nitrate film, cellulose ester film, poly(vinyl acetal) film, polystyrene film, poly(ethylene terephthalate) film, polycarbonate film and related films or resinuous materials, as well as glass, paper, metal and the like.
  • a flexible support is employed, especially a paper support, which can be partially acetylated or coated with baryta and/or an alpha-olefin polymer, particularly a polymer of an alpha-olefin containing two to 10 carbon atoms such as polyethylene, polypropylene, ethylenebutene copolymers and the like.
  • the silver halide emulsions used with this invention may be unwashed or washed to remove soluble salts. 1n the latter case, the soluble salts may be removed by chill-setting and leaching or the emulsion may be coagulation-washed, e.g., by the procedures described in U.S. Pat. No. 2,618,556 by Hewitson et al., 2,614,928 by Yutzy et al., 2,565,418 by Yackel, 3,241,969 by Hart and 2,489,341 by Waller et al.
  • the photographic and other hardenable layers used in the practice of this invention can be hardened by various organic or inorganic hardeners, alone or in combination, such as the aldehydes, and blocked aldehydes, ketones, carboxylic and carbonic acid derivatives, sulfonate esters, sulfonyl halides and vinyl sulfonyl ethers, active halogen compounds, epoxy compounds, aziridines, active olefins, isocyanates, carbodiimides, mixed-function hardeners and polymeric hardeners such as oxidized polysaccharides, e.g., dialdehyde starch, oxyguar gum and the like.
  • various organic or inorganic hardeners such as the aldehydes, and blocked aldehydes, ketones, carboxylic and carbonic acid derivatives, sulfonate esters, sulfonyl halides and vinyl sulfonyl ethers, active halogen compounds,
  • the photographic emulsions and elements can contain various colloids alone or in combination as vehicles, binding agents and various layers.
  • Suitable hydrophilic materials include both naturally occurring substances such as proteins, for example, gelatin, gelatin derivatives, cellulose derivatives, polysaccharides such as dextran, gum arabic and the like; and synthetic polymeric substances such as water-soluble polyvinyl compounds like poly(vinylpyrrolidone), acrylamide polymers and the like.
  • the described photographic emulsion layers and other layers of a photographic element employed in the practice of this invention can also contain, alone or in combination with hydrophilic, water-permeable colloids, other synthetic polymeric compounds such as dispersed vinyl compounds such as in latex form and particularly those which increase the dimensional stability of the photographic materials.
  • Suitable synthetic polymers include those described, for example, in U.S. Pat. Nos. 3,142,568 by Nottorf issued July 28, 1964; 3,193,386 by White issued July 6, 1965; 3,062,674 by Houck et a1. issued Nov. 6, 1962; 3,220,844 by Houck et al. issued Nov. 30, 1965; 3,287,289 by Ream et a1. issued Nov.
  • the photographic elements used with this invention may contain antistatic or conducting layers; such layers may comprise soluble salts, e.g., chlorides, nitrates, etc., evaporated metal layers, ionic polymers such as those described in U.S. Pat. No. 2,861,056 by Minsk and 3,206,312 by Sterman et al. or insoluble inorganic salts such as those described in U.S. Pat. No. 3,428,451 by Trevoy.
  • soluble salts e.g., chlorides, nitrates, etc.
  • evaporated metal layers ionic polymers such as those described in U.S. Pat. No. 2,861,056 by Minsk and 3,206,312 by Sterman et al.
  • insoluble inorganic salts such as those described in U.S. Pat. No. 3,428,451 by Trevoy.
  • the photographic layers employed in the practice of this invention can contain plasticizers and lubricants such as polyalcohols, e.g., glycerin and diols of the type described in Milton et al., U.S. Pat. No. 2,960,404; fatty acids or esters such as those described in Robijns, U.S. Pat. No. 2,588,675 and Duane, U.S. Pat. No. 3,121,060; and silicone resins such as those described in DuPont, British Pat. No. 955,061.
  • plasticizers and lubricants such as polyalcohols, e.g., glycerin and diols of the type described in Milton et al., U.S. Pat. No. 2,960,404; fatty acids or esters such as those described in Robijns, U.S. Pat. No. 2,588,675 and Duane, U.S. Pat. No. 3,121,060; and silicone resins such as those described in
  • the photographic layers employed in the practice of this invention may contain surfactants such as saponin; anionic compounds such as alkyl aryl sulfonates described in U.S. Pat. No. 2,600,831 by Baldsiefen; amphoteric compounds such as those described in U.S. Pat. No. 3,133,816 by Ben-Ezra; and
  • inventions may contain matting agents such as starch, titanium dioxide, zinc oxide, silica, and polymeric beads including beads of the type described in US. Pat. Nos. 2,992,101 by Jelley et a1. and 2,701,245 by Lynn.
  • matting agents such as starch, titanium dioxide, zinc oxide, silica, and polymeric beads including beads of the type described in US. Pat. Nos. 2,992,101 by Jelley et a1. and 2,701,245 by Lynn.
  • the dyes and other addenda used in the practice of this invention may be added from water solutions or suitable organic solvent solutions may be used.
  • the compounds can be added using various procedures including those described in US. Pat. Nos. 2,912,343 by Collins et a1.; 3,343,605 by McCrossen et al.; 2,996,287 by Audran; and 3,425,835 by Johnson et al.
  • a method of manufacture of a photographic element useful as a direct-positive printout element which comprises:
  • Am emulsion according to claim 8 which is light fogged to a visible density of about 0.5 to about 1.5 before addition of the electron-acceptor compound. 7 7 g 10.
  • a photographic element useful as a direct-positive printout element which comprises a support and an emulsion according to claim 6.
  • a photographic element useful as a direct-positive printout element which comprises a support and an emulsion according to claim 7.
  • a photographic element useful as a direct-positive printout element which comprises a support and an emulsion according to claim 8.
  • a photographic element useful as a direct-positive printout element which comprises a support and an emulsion according to claim 9.
  • a photographic element useful as a direct-positive printout element which comprises a support and an emulsion according to claim l0.
  • a photographic element useful as a direct-positive printout element which comprises a support and an emulsion according to claim 1 l.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
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US56703A 1970-07-20 1970-07-20 Direct-positive print-out silver halide emulsion fogged to visible density Expired - Lifetime US3650758A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4207103A (en) * 1978-06-26 1980-06-10 Eastman Kodak Company Photographic print-out silver halide process
US4614801A (en) * 1984-04-09 1986-09-30 E. I. Du Pont De Nemours And Company Direct positive dyes made from 3-indolizine carboxaldehyde
US4701398A (en) * 1984-04-09 1987-10-20 E. I. Du Pont De Nemours And Company Photographic film containing direct positive dyes made from 3-indolizine carboxaldehyde
US5501946A (en) * 1992-07-29 1996-03-26 Fuji Photo Film Co., Ltd. Pre-fogged direct reversal silver halide photographic material

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3772030A (en) * 1972-02-29 1973-11-13 Eastman Kodak Co Direct-positive emulsion containing internally fogged, silver halide grains free of surface fog and a desensitizing compound

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3501310A (en) * 1966-03-11 1970-03-17 Eastman Kodak Co Direct positive silver halide emulsions containing compounds which accept electrons and spectrally sensitize the emulsion
US3526507A (en) * 1965-04-28 1970-09-01 Keuffel & Esser Co Autopositive reproduction material

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3526507A (en) * 1965-04-28 1970-09-01 Keuffel & Esser Co Autopositive reproduction material
US3501310A (en) * 1966-03-11 1970-03-17 Eastman Kodak Co Direct positive silver halide emulsions containing compounds which accept electrons and spectrally sensitize the emulsion

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4207103A (en) * 1978-06-26 1980-06-10 Eastman Kodak Company Photographic print-out silver halide process
US4614801A (en) * 1984-04-09 1986-09-30 E. I. Du Pont De Nemours And Company Direct positive dyes made from 3-indolizine carboxaldehyde
US4701398A (en) * 1984-04-09 1987-10-20 E. I. Du Pont De Nemours And Company Photographic film containing direct positive dyes made from 3-indolizine carboxaldehyde
US5501946A (en) * 1992-07-29 1996-03-26 Fuji Photo Film Co., Ltd. Pre-fogged direct reversal silver halide photographic material

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FR2101790A5 (fr) 1972-03-31
BE770218A (fr) 1971-12-01

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