Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
  • G03C1/34—Fog-inhibitors; Stabilisers; Agents inhibiting latent image regression
  • G03C1/346—Organic derivatives of bivalent sulfur, selenium or tellurium

Definitions

• This invention relates to stabilized photographic compositions. More particularly, this invention relates to the stabilization of photographic silver halide emulsions. In a specific aspect, this invention relates to inhibiting development of spontaneous fog without adversely affecting the sensitivity of a photographic silver halide emulsion.
• organic disulfides have been described as being effective in preventing an increase in fog and to stabilize or control the keeping quality of photographic emulsions.
• many of these organic disulfides are not elTective antifoggants unless they are used in combination with other materials and still others cause objectionable desensitization of the emulsion.
• US. Patent 2,440,110 discloses that organic disulfides such as diphenyl disulfide or ditolyl disulfide must be used in combination with sulfinic or seleninic acids or their salts to obtain acceptable stabilization. It is evident, therefore, that the state of the art will be enhanced by providing photographic silver halide emulsions which are stabilized by organic disulfides which are not subject to the aforementioned deficiencies.
• Another object of this invention is to provide a method for stabilizing photographic silver halide emulsions.
• Another object of this invention is to provide a method of stabilizing photographic silver halide emulsions without adversely affecting, to any substantial extent, the sensitivity of the emulsion.
• Still another object of this invention is to provide photographic silver halide emulsions which are stabilized with organic disulfides.
• each R is a trifluoromethyl, alkyl or aryl radical. It is obvious that the 0 all group is an acyl radical derived from an aliphatic or aromatic carboxylic acid.
• the R groups except in the case of trifluoromethyl, are hydrocarbon and generally contain up to about 20, preferably up to 10, carbon atoms.
• the preferred alkyl groups contain 1-10 carbon atoms.
• Suitable R groups include, for example, trifluoromethyl, methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, octyl, decyl, dodecyl, eicosyl, phenyl, tolyl, naphthyl, anthryl, and the like.
• examples of the disulfide employed in the practice of this invention include bis(p-acetamidophenyl)disulfide,
• a convenient method for preparing the bis(p-acylamidophenyl)disulfide stabilizers employed in practicing this invention comprises reacting 4,4'-diamidodiphenyl disulfide with the appropriate carboxylic acid anhydride as represented by the following equation:
• each R is as defined hereinbefore.
• the reaction generally takes place at relatively mild temperatures, for example, temperatures up to about C. Normal atmospheric pressures are preferably employed although pressures substantially below or above normal atmospheric pressures can be used. If desired, the reaction can be carried out in an inert organic vehicle, and will go to completion in a relatively short period, generally not more than about 4 hours.
• the resulting bis(p-acylamidophenyl)disulfides can then be isolated by conventional procedures, for example, filtering, Washing and drying. The synthesis of bis(p-acetamidophenyl)disulfide by this procedure is shown in Berichte 38, p.
• the stabilizing concentration of the bis(p-acylamidophenyl)disulfide employed in a given emulsion is subject to wide variation, depending upon the effects desired, degree of ripening, silver content of the emulsion, etc. In general, a concentration in the range of about .001 to about 10, preferably about .1 to about 1 gram per mole of silver halide is adequate.
• the stabilizer can be incorporated directly into the silver halide emulsion layer or it can be present in an adjacent layer. It is generally desirable to use higher concentrations of stabilizer when it is used in an adjacent layer rather than in the silver halide emulsion layer. Exposure of the treated emulsion in conventional photographic testing apparatus such as an intensity scale sensitometer, will reveal the most advantageous concentration for the present stabilizers in a particular emulsion. Such techniques are well known to those skilled in the art.
• the stabilizers of this invention can be added to the photographic composition using any techniques suitable for this purpose. For example, they can be dissolved in a suitable solvent and added directly to the silver halide emulsion or they can be added to the emulsion in the form of a dispersion similar to the technique used to incorporate certain types of color forming compounds (couplers) in a photographic emulsion.
• the solvent should be selected so that it has no harmful effects upon the emulsion, in accordance with usual practice, and organic solvents or diluents are preferred. Examples of suitable solvents or diluents include ethanol, acetone or the like.
• the stabilizing addenda employed in the practice of this invention can be used in various kinds of photographic emulsions. In addition to being useful in orthochromatic, panchromatic and infrared emulsions, they are also useful in X-ray and other non-optically sensitized emulsions. They can be added to the emulsions before or after any optically sensitizing dyes which may be used. They are particularly effective in sulfur and gold sensitized silver halide emulsions. Various silver salts can be used as sensitive salts, including, for example, silver bromide, silver iodide, silver chloride or mixed silver halides such as silver chlorobromide, silver bromoiodide or silver chloroiodide.
• the subject addenda can be used in emulsions intended for color photography, for example, emulsions containing color forming couplers or emulsions to be developed by salts containing couplers or other color generating materials.
• gelatin In the preparation of the silver halide dispersions employed for preparing silver halide emulsions there can be employed as the dispersing agent for the silver halide in its preparation, gelatin or some other colloidal material such as colloidal albumin, a cellulose derivative or a synthetic resin, for example, a polyvinyl compound, although gelatin is preferred.
• the photographic emulsions stabilized according to this invention can be coated on a wide variety of supports.
• Typical supports include those generally employed for photographic elements, as exemplified by cellulose nitrate film, cellulose acetate film, polyvinyl acetal film, polystyrene film, polyethylene terephthalate film and related films of resinous materials as well as glass, paper, metal, wood and the like.
• Supports such as paper that are coated with a-olefin polymers, particularly polymers of a-olefins containing 2-10 carbon atoms, as for example, polyethylene, polypropylene, ethylene butene copolymers and the like, can also be employed.
• the photographic emulsions and elements can also contain additional additives, particularly those known to be beneficial in photographic emulsion-s, as exemplified by optical sensitizers, speed increasing materials, gelatin hardeners, plasticizers and the like.
• Example 1 The disulfides disclosed herein stabilize photographic emulsions against increases in fog and decreases in speed even upon storage at increased temperatures and humidity.
• bis(p-acetamidophenyl)disulfide is incorporated into a negative, high speed gelatino silver bromoiodide emulsion containing a yellow dye forming coupler. The emulsion is coated on a cellulose acetate film base.
• three samples of the identical emulsion, one sample containing no antifoggant compound, one containing ditolyl disulfide and one containing diphenyl disulfide are coated on cellulose acetate film base in the same manner. Samples of the prepared photographic elements are then incubated for 7 days at F. and 50% relative humidity, exposed for second in the form of film strips in an intensity scale sensitometer (Kodak Type Ib) and developed for 12 minutes at 75 F.
• the developer employed has the following formula:
• a negative silver image and a yellow dye image is formed.
• the silver image and the residual silver halide are removed by treatment with a conventional ferricyanide bleach followed by a hypo fixing bath leaving a yellow negative dye image.
• the bis(pacylamidophenyl)disulfides of this invention impart substantial stabilizing and antifogging properties to photographic silver halide emulsions. It is also significant to note that the practice of this invention does not result in substantial loss in speed with the improved stability.
• Table 1 illustrates that aryl disulfides having unsubstituted aromatic rings or aromatic rings containing such substituents as alkyl groups are ineffective to impart stabilizing or antifoggant properties to photographic silver halide emulsions.
• such aryl disulfides require the presence of various sulfinic or seleninic acids or salts to exhibit any stabilizing effects. Such additional additives are, of course, not necessary with the specific organic disulfides employed in the practice of this invention.
• Example 2 deleterious afiFect on the stability and/or speed of the photographic silver halide emulsion.
• Example 3 deleterious afiFect on the stability and/or speed of the photographic silver halide emulsion.
• the procedure of Example 3 is repeated with bis(p-acetamidophenyl)disulfide and bis[o-(N-ethyl)acetamidophenyl] disulfide which has the formula:
• Example 3 related structurally to bis(p-acetamidophenyl)disulfide shows a substantial deleterious effect upon the speed and/ or fog of a photographic emulsion when it is used in place of the latter. This same deleterious effect is exhibited by other ortho substituted aryl disulfides such as di-o-formylethylaminodiphenyldisulfide when they are employed in the above procedure.
• this invention provides silver halide emulsions that are stabilized with antifoggant addenda which do not cause substantial desensitization or loss in speed.
• R-ji-EO s s Q-E-E-R where each R is selected from the group consisting of alkyl, trifluoromethyl and aryl.
• Rii M EAR where each R is selected from the group consisting of alkyl, trifluoromethyl and aryl.
• each R is selected from the group consisting of alkyl, trifluoromethyl and aryl.
• each R is an alkyl radical containing up to 20 carbon atoms.
• each R is an alkyl radical containing 1-10 carbon atoms.
• each R is an alkyl group containing 1-10 carbon atoms.
• each R is an aryl radical containing up to 20 carbon atoms.
• each R is an alkyl radical containing up to 20 carbon atoms.
• a sulfur and gold sensitized negative, high speed gelatino silver bromoiodide emulsion which is stabilized with about .09 gram per mole of silver halide of bis(pacetamidophenyl) disulfide.

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• Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• General Physics & Mathematics (AREA)
• Silver Salt Photography Or Processing Solution Therefor (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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Cited By (18)

Citations (2)

• 1964
  • 1964-12-29 US US421994A patent/US3397986A/en not_active Expired - Lifetime
• 1965
  • 1965-12-22 DE DE19651472883D patent/DE1472883A1/de active Pending
  • 1965-12-29 GB GB55099/65A patent/GB1110371A/en not_active Expired
  • 1965-12-29 FR FR44111A patent/FR1467298A/fr not_active Expired

Patent Citations (2)

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