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
• • 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
  • G03C1/33—Spot-preventing agents

Definitions

• ABSTRACT Azodicarbonamidine salts as a class inhibit fog formation in silver halide emulsions when contacted there- I with.
• fog Metallic silver appearing in non-exposed areas of a silver halide photographic emulsion layer after development is commonly called fog.
• This fog may be caused by the action of certain compounds in the emulsion, by the composition and the nature of the developer, by atmospheric oxidation, storage, etc.
• the type of packaging used for the photographic film can affect fog formation, as can the type of base upon which the silver halide photographic emulsion is spread. It is probable, for example, that a supporting polyester film contributes more greatly to fog in a silver halide emulsion layer than does a supporting cellulose ester film.
• the storage of emulsions at high temperatures and humidities favors fog formation.
• fog may generally appear as a uniform blackening of emulsion layers
• these layers often show small areas where the fog is darker or lighter than in the surrounding areas. Those small areas are commonly called sensitization or desensitization spots, or more simply black spots" or white spots.
• Such spots are often related to the presence in the emulsion layer (or in an adjacent layer) of metallic particles, such 'as particles of iron, copper, tin or their derivatives. These particles are, in turn, related to the type of base used (for instance polyester) or are caused by the environment wherein the material has been prepared or used.
• ffog fog and spots
• an azodicarbonamidine salt preferably have the formula wherein R1, R R and R independently are hydrogen, alkyl or aryl, and X represents an equivalent of anion, such as chloride, nitrate, sulfate or picrate.
• Formula I can also be written 1 R, IA
• the emulsion maybe placed in a layer adjacent an emulsion layer, or may be introduced into developer baths or pre-developer baths.
• Preferred azodicarbonamidine salts for this purpose are those defined in Fonnulae I and IA above.
• the invention relates to a method for inhibiting fog in a silver halide photographic emulsion which comprises contacting the emulsion with an azodicarbonamidine salt, preferably of the type defined in Formulae I and IA.
• an azodicarbonamidine salt preferably of the type defined in Formulae I and IA.
• the ability to inhibit fog in siliver halide emulsions is shared by azodicarbonamidines as a class.
• the invention relates to novel azodicarbonamidine salts which are useful as fog inhibitors for silver halide emulsions and which are characterized by the formula R1 NH NH R3 I i ii- 13 .21: H H/ ⁇ R4 wherein R R R and R independently are hydrogen,
• R R R and R alkyl or aryl with the proviso that at least one (and preferably two or more) of R R R and R is different from hydrogen, and X is an equivalent of anion.
• Formula II cal also be written wherein R R R R and X are as defined next above.
• azodicarbonamidine salts may be prepared by oxidizing, e. g., with potassium permanganate in aqueous nitric acid, an N-substituted amino guanidine obtained in a known way, e.g., by reacting an N-substituted-S-methyl isothiourea with hydrazine, or the reduction product of an N-subst ituted nitroguanidine with high pressure hydrogen in the presence of a platinum oxide catalyst.
• an N-substituted-S-methylisothiourea may be reacted in a suitable solvent, such as pyridine, with an N-substituted amino guanidine; the
• azodicarbonamidine salts as a class have been found to inhibit fog in silver halide photographic emulsions.
• the choice of groups R R R and R will vary to some extent the fog inhibiting ca pacity and solubilities of compounds of the invention, and .it is preferred that the alkyl or aryl groups which maybe represented by each of R1, R2, R and R in formulas I, IA, II and II A above be limited respectively to no more than 4 and 14 carbon atoms.
• the selection of the anion X may also effect to a small extent these properties, the selection of X is not critical to the invention.
• Chloride e.g., halide
• nitrate e.g., sulfate
• picrate e.g., nitrate
• sulfate e.g., nitrate
• picrate e.g., nitrate
• picrate e.g., nitrate
• picrate e.g., nitrate
• picrate e.g., nitrate
• picrate e.g., nitrate, sulfate and picrate
• the compounds of the present invention are -solvent-soluble; e.g., they are soluble in the primarily polar solvents employed in photography, including, for example, water, alcohol, and dimethylformamide.
• the permanganate addition was continued until it began to impart a dark coloration which lasted for some seconds; concurrently a yellow crystalline solid formed.
• the mixture was rapidly filtered and when the product was almost dry, it was washed with 100 cc of ethanol. It was dried under vacuum at 30C. 2.05 g of very small yellow crystals were obtained, with a decomposition point of 162C, formed by N,N-dimethylazodicarbonamidine nitrate.
• the product, in the form of a yellow powder was highly soluble in water, soluble in dimethylformamide, insoluble in alcohol, in acetone and in non-polar solvents.
• azodicarbonamidine nitrate in water was treated with a slight excess of a saturated solution of picric acid to cause nearly quantitative separation of N,N'-dimethylazodicarbonamidine picrate in the form of very fine, short needles with an intense red color.
• the decomposition point was 189C.
• the product was highly soluble in dimethylformamide, and slightly soluble in ethanol.
• N,Ndiethyl-azodicarbonamidine nitrate Into a 750 cc covered flask, equipped with mechanical stirrer and a thermometer and placed on a refrigerating bath, were introduced 35 cc of 70% nitric acid and 35 cc of water containing in solution, the product of the reduction (obtained with high pressure hydrogen in presence of platinum oxide) of 0.1 moles of N-ethylnitroguanidine. The solution was cooled to 5C and at this temperature small quantities of potassium permanganate in powder form were added very carefully. The resulting exothermic reaction caused the fonnation of a large amount of foam, and the solution rapidly attained an intense yellow coloration. When almost twothirds of the oxidant was added, a light voluminous yellow solid began to separate out. At the end of the reaction the mixture was rapidly filtered nearly dry; then it was washed with 100 cc of ethanol and dried under vacuum at 35C.
• N,N'-diphenyl-azodicarbonamidine picrate Into a 750 cc flask equipped with mechanical stirrer and a thermometer and placed on a refrigerating bath were introduced 21.3 g (0.01 moles) of N-phenylamino-guanidine nitrate, and 100 cc of nitric acid and 100 cc of water to form a solution. The solution was cooled to 2C and at this temperature, small amounts of potassium permanganate in powder were added very carefully. An exothermic reaction occurred with gas development. In two hours, 9.7 g of permanganate (0.061 moles) were added.
• the mixture was rapv idly filtered, maintaining cold conditions, and the filtrate was treated with an excess of a saturated solution of picric acid.
• a red fluffy solid separated out and was collected on a vacuum filter, dried under vacuum at 30C, and ground twice with 250 cc of ether. The mixture was filtered again. After drying under vacuum at 30C thereremained 12.3 g (equal to 34% of the theoretical yield) of a red' powder, melting at 95C, with decomposition.
• the solubility of the product was excellent in dimethylformamide, good in alcohol and in acetone, and slight in cold water.
• the product was then very rapidly crystallized from boiling water. By crystallization an extremely electrifyable powder (e.g., capable of maintaining an electric charge) of a dark yellow color with a melting point of 154C (with decomposition)'was obtained.
• the solubility was similar to that of the raw product.
• N,N-di-m-tolyl-azodicarbonamidine picrate Into a 750 cc flask equipped with mechanical stirrer and a thermometer and placed on a refrigerating bath were introduced 30 cc of 70% nitric acid and 35 cc of water, containing,”in solution, the reduction product (obtained with high pressure hydrogen and platinum oxide) of- 0.05 moles of N-m-tolyl,N'-nitroguanidine. The solution was cooled to -3C and at this temperature, small amounts of powdered potassium pennanganate were added very carefully. An exothermic reaction occurred with gas development, and the solution rapidly became red.
• N,N'di-a-naphthyl-azodicarbonamidine nitrate Into a 750 cc flask equipped with mechanical stirrer and a thermometer and placed on a refrigerating bath were introduced 40 cc of 70% nitric acid containing dissolved 13.15 g (0.05 moles) of N'-a-naphthyl,N'- aminoguanidine nitrate. The solution was cooled to 2C and at this temperature small amounts of powdered potassium permanagante were carefully added. An exothermic reaction occurred, with gas development, and the solution rapidly turned a dark red. The amount of KMnO. used was 4.85 g (0.6 moles per mole of aminoguanidine).
• N,N'-di-(methyl,phenyl)-azodicarbonamidine picrate N-methyl-N-phenyl-N'-aminoguanidine nitrate (11.35 g, 0.05 moles) were dissolved in 30 cc of nitric acid and introduced into a 750 cc flask,,equipped with mechanical stirrer and a thermometer and placed on a refrigerating bath. The temperature was brought to 3C and kept constant while 4.85 g of powdered potassium permanganate were carefully added in small portions over about a one hour period. The addition was performed very carefully to avoid overheating from the resulting exotherm. Gas development was observed.
• N-ethylN-phenyl-azodicarbonamidine picrate 4.92 g (0.02 moles) of N-ethyl-S-methyl-isothiourea iodide and 5.84 g (0.02 moles) of N-phenyl-N'- aminoguanidine iodide, and 20 cc of pyridine were introduced into a 250 cc flash equipped for reflux. The mixture was heated to the boil. After a few minutes it was clearly evident from the odor of methylmercaptan that the reaction had begun. Heating was continued until the development of methylmercaptan ceased.
• the emulsions of the invention may contain various synthetical polymers as colloidal liquids in substitution for, or in addition to the commonly employed gelatin.
• Exemplary of such polymers are dextrane, polyvinylalcohol, polyvinylpyrrolidone, partially hydrolized polyvinylacetate, polyethylacrylate, polymethylmetacrylate and polyamides.
• the emulsions of the invention may be chemically sensitized by remelting with naturally activated gelatin, by addition of chemical sensitizers such as thiosulfate, allylthiourea, thiocyanates, thiosulphonates, etc., by employment of salts of noble metals (for example gold salts), etc.
• the emulsions may contain spectral sensitizers such as cyanine and mercocyanine dyes and may contain couplers, surface active agents, hardeners, stabilizers, antifog agents, plasticizers, anti-oxidants, development accelerators and, in general, the various additives commonly used' in the production of silver halide photographic emulsions.
• Such emulsions may be spread upon any suitable support such as polystyrene, polyester, cellulose acetate, polycarbonate, paper, glass, etc.
• the azodicarbonamidine salts of the present invention are Y particularly suitable for the prevention of fog usually occurring when a polyester film support (for example, polyethyleneterephthalate) is used or when unusually rapid processes for the spreading and drying of the emulsions are used.
• azodicarbonamidine salts in sil- -ver halide emulsions may be conveniently accomplished by adding them to the emulsions during preparation thereof. Even though it is preferable that the azodicarbonamidine salts be incorporated into silver halide emulsion layers, fog and spots are avoided or minimized if the salts are at least put into contact with ide layer or in an adjacent layer will vary depending 6 about 2.5 millimoles of an azodicarbonamidine salt such as those exemplified above per gram-atom of silver.
• Examples 1-13 have been evaluated photographically together with previously known azodicarbonamide salts representing further examples of such salts useful as fog-inhibitors according to the present invention. These compounds are azodicarbonamidine nitrate (Example 14), azodicarbonamidine sulfate (Example 15), azodicarbonamidine chloride (Example 16) and azodicarbonamidine picrate (Example l7).
• EXAMPLE 18 The solubility of compounds l-l7 in common solvents used in photography (water, ethyl alcohol and dimethylformamide (DMF)) at room temperature (about 20C) was measured. The results are schematically reported in Table 1 wherein indicates a solubility greater than 1 per cent and a solubility less than 0.05%.
• Metol Water to Table 2 reports the results of sensitometric test performed on fresh film samples and on film samples stored respectively for 15 hours at 72C, and at 30% RH.
• a high sensitivity silver halide emulsion containing 1.8 mole of Ag! and 98.2 mole of AgBr was divided into several portions. To these portions were added respectively the compounds reported in Table 4. The resulting emulsion samples were then spread on a polyester support'previously thinly coated with gelatin containing iron powder. Samples of the resulting films were developed in Ferrania R-l4 developer (Example 19) for 3 at 20C. The capacity of the compounds to inhibit spot formation was evaluated by counting the number of the spots per unit area in several areas of 1.
• a silver halide photographic emulsion containing a fog inhibiting amount of an azodicarbonamidine salt was evaluated by counting the number of the spots per unit area in several areas of 1.
• a photographic element which includes a silver halideemulsion layer. said emulsion layer containing a 7 15 16 fog inhibiting amount of an azodicarbonamidine salt, or sion layer. v said emulsion layer having an adjacent layer containing 9.
• the photographic element according to claim 7 wa fog inhibiting amount of an azodicarbonamidine salt.
• said azodicarbonamidine salt is in a layer adja- 8.

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• Engineering & Computer Science (AREA)
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• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 1971
  • 1971-04-29 IT IT50035/71A patent/IT942090B/it active
• 1972
  • 1972-04-18 US US00245681A patent/US3819380A/en not_active Expired - Lifetime
  • 1972-04-19 CA CA140,044A patent/CA1001885A/en not_active Expired
  • 1972-04-26 JP JP4210772A patent/JPS5539822B1/ja active Pending
  • 1972-04-27 AR AR241697A patent/AR194100A1/es active
  • 1972-04-28 CH CH633772A patent/CH571234A5/xx not_active IP Right Cessation
  • 1972-04-28 BE BE782824A patent/BE782824A/xx not_active IP Right Cessation
  • 1972-04-28 FR FR7215218A patent/FR2136777A5/fr not_active Expired
  • 1972-04-28 GB GB1997472A patent/GB1383386A/en not_active Expired
  • 1972-04-28 DE DE2221024A patent/DE2221024C3/de not_active Expired

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