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
  • G03C1/08—Sensitivity-increasing substances
  • G03C1/10—Organic substances
• • 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
  • G03C1/015—Apparatus or processes for the preparation of emulsions
• • 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
  • G03C1/08—Sensitivity-increasing substances
  • G03C1/09—Noble metals or mercury; Salts or compounds thereof; Sulfur, selenium or tellurium, or compounds thereof, e.g. for chemical sensitising
  • G03C2001/091—Gold
• • 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
  • G03C1/08—Sensitivity-increasing substances
  • G03C1/09—Noble metals or mercury; Salts or compounds thereof; Sulfur, selenium or tellurium, or compounds thereof, e.g. for chemical sensitising
  • G03C2001/097—Selenium
• • 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
  • G03C2200/00—Details
  • G03C2200/44—Details pH value

Definitions

• the present invention concerns a silver halide photographic emulsion, and particularly a silver halide emulsion sensitised by means of a novel combination of sensitising compounds, and the process for obtaining such an emulsion.
• the sensitisation of the emulsions is limited by the quantity of sensitising compounds which can be added to the emulsion without causing a significant increase in fogging.
• Hydroquinone and derivatives of hydroquinone are known for their silver halide reducing properties. They are usually used in photographic processing as photographic product developing substances. Derivatives of particular interest for this type of application are described in Chimie et Physique Photographiques, Glafkides, page 154, and in a large number of patents such as US patent 4 377 634.
• Hydroquinone derivatives can also be incorporated into a photographic product.
• US patent 4 614 707 describes a colour reversible photographic product which comprises several layers of silver halide emulsion, each of these layers containing a dye-forming coupler. These photosensitive layers are separated by intermediate layers comprising silver halides which do not participate in the formation of the image, and at least one of these intermediate layers contains a hydroquinone derivative substituted by a sulpho, carboxyl, sulphoalkyl or carboxyalkyl group.
• European patent 209 010 describes a high-contrast negative photographic product obtained using a monodisperse emulsion consisting of silver halide grains with a size of less than 0.7 ⁇ m and which are such that the latent image forms on the surface of these grains.
• This emulsion also comprises an arylhydrazide contrast amplifier and a quantity of a hydroquinone derivative for reducing sensitivity to pressure.
• US patent 3 192 146 describes a silver halide photographic emulsion sensitised by a novel combination of chemical sensitisers which comprises a thioether and a hydroquinone derivative associated with a compound capable of salting out or forming bisulphite ions. Such a combination enables the sensitivity of a silver halide photographic emulsion to be increased.
• the object of the present invention is to increase the sensitivity of a silver halide emulsion without changing the fogging level, by associating a conventional chemical sensitisation using sulphur, gold or selenium with a sensitisation by reduction by means of a polyhydroxybenzene under particular pH conditions.
• the present invention resolves the problem related to the increase in fogging level when sensitisation by reduction is used.
• the present invention concerns a silver halide photographic emulsion chemically sensitised by means of a sensitiser chosen from among sulphur, gold and selenium and at least one reduction sensitiser characterized in that the reduction sensitiser is a polyhydroxybenzene, and in that the pH of the emulsion after the addition of the different chemical sensitisers is between 7 and 10.
• a sensitiser chosen from among sulphur, gold and selenium
• at least one reduction sensitiser characterized in that the reduction sensitiser is a polyhydroxybenzene, and in that the pH of the emulsion after the addition of the different chemical sensitisers is between 7 and 10.
• the polyhydroxybenzene according to the present invention is preferably a hydroquinone derivative.
• hydroquinone derivatives are, for example, 2-(2'-octodecyl)-5-sulphohydroquinone, 2,5-didodecylhydroquinone, 2,5-bis(1,1,3,3-tetramethylbutyl)hydroquinone or a salt of these compounds. These hydroquinone derivatives can be used alone or in combination.
• the quantities of hydroquinone derivatives may be between 0.05 and 1 mmole per mole of silver, and preferably between approximately 0.1 and 0.6 mmole per mole of silver.
• the hydroquinone derivative is 2-(2'-octodecyl)-5-sulphohydroquinone and the pH of the emulsion is between 7 and 9 and preferably 8 and 9.
• the compounds of sulphur and/or gold and/or selenium which are used for chemically sensitising the emulsion of the invention are conventional compounds such as thiosulphates, thioureas, aurous sulphocyanide, aurothiocyanates, selenoureas, etc. These compounds were described, for example, in Research Disclosure No 308119, December 1989, Section III.
• the quantities of chemical sensitisers containing sulphur, gold or selenium added to the emulsion are determined experimentally in order to obtain an optimally sensitised emulsion.
• the process for preparing such emulsions is comprised of precipitating silver halide grains in a colloid using a solution of silver nitrate and one or more halide salts, and then adding one or more spectral sensitising dyes in order to sensitise the emulsion by one or more chemical sensitising compounds containing sulphur and/or gold and/or selenium and at least one polyhydroxybenzene such as, for example, a hydroquinone derivative.
• the pH of the emulsion is adjusted to a value lying between 7 and 10.
• the spectral sensitising dye or dyes, the chemical sensitising dye or dyes containing sulphur and/or gold and/or selenium and the hydroquinone derivative or derivatives are added to the emulsion in that order.
• the pH is then adjusted by adding a strong base, for example sodium hydroxide.
• the temperature of the sensitised emulsion is raised to between 30 and 90°C and preferably above 50°C, in order to obtain a better adsorption of the different sensitisers.
• a level stage is maintained at a temperature of around 60°C.
• the photographic emulsion may consist of one or more silver halides chosen from amongst silver chloride, bromide and iodide.
• the silver halide grains may have different morphologies, for example tabular, octahedral (faces 111), cubo-octahedral or cubic (faces 100).
• the silver halide emulsion may be spectrally sensitised with conventional spectral sensitising dyes as described for example in Research Disclosure, December 1989, No 308119, Section IV (hereinafter referred to as Research Disclosure).
• These dyes are, for example, cyanine, merocyanine or hemioxodol dyes.
• the quantity of each of the spectral sensitisers differs greatly according to the conditions of use, the quantity of spectral sensitisers is preferably between 0 and 1.4 mmole per mole of silver.
• the emulsions of the present invention may be used in black and white or colour photographic products of different types, such as negative, positive or reversal photographic products.
• these photographic products are colour photographic products, they comprise, in a conventional manner, at least three components which are respective blue, green and red sensitive, providing respectively the yellow, magenta and cyan components of the subtractive synthesis of the colour image.
• Colour photographic products generally comprise a support carrying at least one layer of blue-sensitive silver halide emulsion with which a yellow dye forming coupler is associated, at least one layer of green-sensitive silver halide emulsion with which a magenta dye forming coupler is associated, and at least one red-sensitive silver halide emulsion with which a cyan dye forming coupler is associated.
• the support may be any suitable support used in photographic products.
• Conventional supports comprise polymer films, paper (including polymer-coated paper), glass and metal. Research Disclosure, Section XVII, provides details about supports and ancillary layers in photographic products.
• the silver halide emulsions of the invention, and other layers on the photographic products of this invention may contain, as a carrier, hydrophilic colloids, used alone or in combination with other polymer substances (for example latexes).
• Suitable hydrophilic substances comprise natural substances such as proteins, protein derivatives, cellulose derivatives (for example cellulose esters), gelatin (for example gelatin such as cattle bone or tanned gelatin treated by means of a base or gelatin such as pigskin gelatin treated with an acid), gelatin derivatives (for example acetylated gelatin, phthalylated gelatin, etc), polysaccharides such as dextran, gum arabic, zein, casein, pectin, collagen derivatives, collodion, agar-agar and albumin.
• Surfactants can be incorporated in a layer of photographic emulsion or in another hydrophilic colloidal layer of the photographic product as a coating adjuvant, for example in order to prevent the accumulation of static charges, to improve lubrication properties, to improve the dispersion of the emulsion, to prevent adhesion, and/or to improve the sensitometric properties such as an increase in contrast or the sensitisation or acceleration of development.
• the photographic emulsion of the present invention may contain dye image forming couplers, that is to say compounds capable of reacting with an aromatic amine oxidation product (generally a primary amine) to form a dye.
• dye image forming couplers that is to say compounds capable of reacting with an aromatic amine oxidation product (generally a primary amine) to form a dye.
• Non-diffusible couplers containing a ballast group are desirable. It is possible to use either couplers with four equivalents or couplers with two equivalents.
• couplers enabling the colours to be corrected, or couplers releasing a development inhibiter during development referred to as DIR couplers).
• the photographic products of the invention may contain, amongst other things, optical brighteners, anti-fogging compounds, tanning agents, stabilising agents or absorption and/or diffusion agents as described in Sections V, VI, VIII, XI, XII and XVI of the above-mentioned Research Disclosure.
• the products of the invention after being exposed, undergo photographic processing for developing the silver latent image and a colour image, in the presence of a coupler, which, in certain cases, may be incorporated in the photographic product.
• Development takes place by means of a reducing compound which, by oxydo-reduction reaction, transforms the exposed silver halide grains into metallic silver grains.
• the oxidised form of the reducing compound then reacts with the coupler to form a dye.
• reducing compounds are chosen from amongst the aromatic primary amines such as paraphenylene diamines, aminophenols, etc. These compounds may be used alone or in a mixture, or with ancillary developers.
• This bath may, in addition, contain a stabiliser such as sulphites, a buffer such as carbonates, boric acid, borates or alkanolamines.
• an AgBr tabular grain emulsion was prepared as follows:
• a step consisting of the nucleation of the grains was carried out at 45°C and with a pH of 1.8 and pAg of 9, by introducing, over 15 seconds by the double-jet method, a 0.6 M solution of AgNO3 and a 0.6 M solution of NaBr.
• the emulsion was then cooled to 40°C. After washing of the emulsion, the pH was adjusted to 6.0 and the pAg to 8.
• a pure tabular grain bromide emulsion was obtained, having an equivalent circular diameter of 2.0 ⁇ m and a thickness of 0.11 ⁇ m.
• the emulsion thus obtained was separated into four equal parts and each of the parts was treated in accordance with Table 1.
• the hydroquinone derivative used in this example was the sodium salt of [2-(2'-octadecyl)-5-sulphohydroquinone (D8N).
• the temperature was increased to 65°C. This temperature was maintained for 15 min, and then the emulsions were cooled to 40°C.
• the emulsions obtained were coated on a cellulose triacetate support with a silver content of 0.807 g/m2, a gelatin content of 3.23 g/m2 and a coupler (C1) in a proportion of 1.05 g/m2. This layer of emulsion was covered with a top coating of gelatin (2.15 g/m2).
• the layer of emulsion was hardened using 1.75% bis(vinylsulphonyl)methane by weight of total gelatin.
• the samples thus obtained were exposed by means of a Kodak® sensitometer fitted with a lamp with a colour temperature of 5500°K for 1/100 seconds.
• the sensitometer was fitted with a "Wratten 9®” filter which transmits light of a wavelength shorter than 460 nm.
• Sensitivity 100(1-log E) where E represents the photographic exposure measured at the point of intersection between the tangent at maximum contrast and a straight line passing through the maximum density.
• the minimum density (Dmin) is equal to the optical density of the support and of the fogging obtained without exposure. Although the value of the minimum density varies according to the use of the photographic product, it must in every case be less than or equal to 0.2.
• Examples 1A to 1E show that, when the pH of the emulsion is increased, an increase in sensitivity is observed which is inevitably accompanied by a not insignificant increase in the fogging level.
• Example 1-C and the examples of the invention 1-I, 1-II, 1-V and 1-VI are compared, it is seen that the addition of the hydroquinone derivative results in an increase in sensitivity compared with Examples 1-A to 1-E and a fogging level which remains lower than that obtained in Example 1-D, where the highest sensitivity was obtained.
• Examples 1-III and 1-IV show that, for a pH of around 8.5, when the quantity of hydroquinone derivative is greater than or equal to 0.32 mmol/mol Ag, the increase in sensitivity of the emulsion is accompanied by an increase in the fogging level greater than that of Example 1-D but which remains acceptable.
• the comparative examples 1-VII and 1-VIII show that, for a pH of 10.5, the advantages of the present invention are no longer observed.
• the emulsion was treated as described in Example 1 except that the hydroquinone derivative was 2.5-didodecylhydroquinone (IDH).
• IDH 2.5-didodecylhydroquinone
• Example 2-I to 2-V the increase in sensitivity compared with the reference examples (without hydroquinone derivative) and a fogging level which always remains lower than that of Example 2-D, where the highest sensitivity was obtained, are observed as before.
• Example 2-VI shows that, when the pH is equal to 9, the quantity of hydroquinone derivative will preferably be less than 0.33 mmol/mol of Ag since, in this particular case, the fogging level is higher than in Example 2-D.
• Example 1 The emulsion of Example 1 treated as described in Example 2 except that the hydroquinone derivative was 2,5 bis(1,1,3,3-tetramethylbutyl)hydroquinone (DOH).
• DOH 2,5 bis(1,1,3,3-tetramethylbutyl)hydroquinone
• Examples 3-I to 3-V show that the addition of DOH at a pH of 8.5 or 9.0 enables the sensitivity of the emulsion to be increased compared with the reference emulsions without increasing the fogging level above that of Example 3-D, where the highest sensitivity was obtained.

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Citations (11)

• 1994
  • 1994-06-09 FR FR9407275A patent/FR2721117B1/fr not_active Expired - Lifetime
• 1995
  • 1995-05-26 EP EP95420137A patent/EP0689091A1/fr not_active Withdrawn
  • 1995-06-08 JP JP7142221A patent/JPH086195A/ja active Pending

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