EP0523464B1 - Emulsion à l'halogénure d'argent comprenant des grains ayant une structure en forme de cratère ou d'entonnoir et procédé de fabrication d'une telle émulsion - Google Patents

Emulsion à l'halogénure d'argent comprenant des grains ayant une structure en forme de cratère ou d'entonnoir et procédé de fabrication d'une telle émulsion Download PDF

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Publication number
EP0523464B1
EP0523464B1 EP92111247A EP92111247A EP0523464B1 EP 0523464 B1 EP0523464 B1 EP 0523464B1 EP 92111247 A EP92111247 A EP 92111247A EP 92111247 A EP92111247 A EP 92111247A EP 0523464 B1 EP0523464 B1 EP 0523464B1
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EP
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Prior art keywords
silver halide
silver
grains
emulsion
bromide
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EP92111247A
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German (de)
English (en)
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EP0523464A1 (fr
Inventor
Marcello Amicucci
Milena Debenedetti
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GlassBridge Enterprises Inc
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Imation Corp
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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
    • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
    • G03C1/07—Substances influencing grain growth during silver salt formation
    • 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
    • G03C1/0051—Tabular grain 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
    • G03C1/015—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
    • G03C1/035—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein characterised by the crystal form or composition, e.g. mixed grain

Definitions

  • the present invention relates to silver halide photographic emulsions, their preparation and their use in photographic films.
  • the present invention relates to spectrally and chemically sensitized silver halide grains having a different halide composition in their structure and principally bounded by [100] and/or [111] crystal faces, on which silver halide protrusions are formed, said protrusions forming at least one crater or hopper structure on at least one crystal face of said silver halide grains.
  • US 4,496,652 refers to the growth of silver halide corners on the [111] crystal faces of tetradecahedral silver halide grains to form regular cubic grains
  • US 4,710,455 refers to silver halide grains having a depression and/or a cavity in each face thereof, obtained by precipitating, on host silver halide grains, a second silver halide salt having a lower solubility than the silver halide salt of the host grains.
  • Other references can be found in Berry and Skillman, Journal of Applied Physics, Vol. 35, No. 7 "Surface Structures and Epitaxial Growths on AgBr Microcrystals", July 1964, in Karasawa, Journal of the Society of Photographic Science and Technology of Japan Vol. 47 No. 4, “Silver Halide Crystals in New Type Photographic Emulsion”; and Suzuky and Ueda "The Active Sites for Chemical Sensitization of Monodisperse AgBr Emulsion", 1973, SPSE Tokyo Symposium.
  • EP 232,160 discloses silver halide emulsions comprising silver halide grains having 8 or 12 concavity on the surface thereof, resulting from the dissolution of the whole (111) and (110) or (nn1) faces, respectively and the consequent deposition of dissolved silver halide on other crystal faces.
  • EP 367,248 discloses silver halide grains having calyxes formed by protrusions grown in parallel to plane faces (or ridge faces) formed along the ridge lines of a host silver halide grain. No mention is made of formation of depressed zone by dissolution of existing surface.
  • a process for preparing a silver halide photographic emulsion comprising chemically and spectrally sensitized hollow or cracked silver halide grains having a crater or hopper structure, said process comprising the following steps:
  • the present invention relates to silver halide photographic emulsions obtained with the process of the present invention.
  • the present invention relates to a process for preparing a silver halide photographic emulsion comprising chemically and spectrally sensitized hollow or cracked grains having a crater or hopper structure, said process comprising the following steps:
  • the host silver halide grains can he provided by any conventional silver halide emulsion the grains of which have a cubic crystal lattice structure and are bounded by at least one [111] and/or [100] crystal face and comprising at least 50%M of silver bromide, in a preferred embodiment at least 80%M of silver bromide, the remaining part comprising less than 20%M of silver iodide, more preferably less than 8% silver iodide, and less than 10%M of silver chloride, more preferably less than 5%M silver chloride. In a more preferred embodiment silver chloride is absent.
  • the most common aspects of silver halide grains are the cubic and the octahedral form.
  • the cubic grains are bounded by six identical crystal faces, usually referred to as [100] crystal faces, according to the well known Miller index employed for describing crystal faces.
  • [100] crystal faces the cubic crystal shape is readily visually identified in regular grains, in grains of more complex shapes the presence of [100] crystal faces can best be verified by a combination of visual inspection and the 90° angle of intersection formed by adjacent [100] crystal faces.
  • the octahedral grains are bounded by eight identical crystal faces, usually referred to as [111] crystal faces, according to the well known Miller index employed for describing crystal faces.
  • [111] crystal faces the crystal faces
  • Miller index employed for describing crystal faces.
  • the octahedral crystal shape is readily visually identified in regular grains, in grains of more complex shapes, the presence of [111] crystal faces can be verified by a combination of visual inspection and the 109.5° angle of intersection formed by adjacent [111] crystal faces. It is important to bear in mind that both the cubic and octahedral grains have exactly the same cubic crystal lattice structure and thus the same internal relationship of silver and halide ions. The two kinds of grains differ only in their surface crystal faces.
  • each surface silver ion lies immediately adjacent five halide ions
  • the surface silver ions at the [111] crystal faces each lies immediately adjacent only three halide ions.
  • silver halide grains can be tetradecahedral, i.e., formed of a combination of [111] and [100] crystal faces.
  • a regular tetradecahedral grain has fourteen crystal faces, six [100] crystal faces and eight [111] crystal faces.
  • the number of said twin planes affects the form of the tabular grain, i.e., a tabular grain having an odd number of twin planes normally has a triangular main surface, a tabular grain having an even number of twin planes normally has a hexagonal main surface.
  • the host silver halide emulsion used in this invention may be a dispersion of silver bromide, silver chloro-bromide, silver iodo-bromide and silver chloro-iodobromide in a hydrophilic binder.
  • Preferred silver halides are silver bromide and silver iodo-bromide containing 1 to 20 %M, preferably 1 to 8 %M silver iodide.
  • the emulsions can be composed of coarse, medium and fine grains and can be monodispersed or polydispersed.
  • the silver halide grains may have any crystal form such as cubical, octahedral, tabular or a mixed crystal form.
  • the silver halide can have a uniform grain size or a broad grain size distribution.
  • the size of the silver halide ranges from about 0.1 to about 5 ⁇ m.
  • the silver halide emulsion can be prepared using a single-jet method, a double-jet method, or a combination of these methods or can be matured using, for instance, an ammonia method, a neutralization method, an acid method, or can be performed an accelerated or constant flow rate precipitation, interrupted precipitation, ultrafiltration during precipitation, etc. References can be found in Trivelli and Smith, The Photographic Journal, Vol. LXXIX, May 1939, pp. 330-338, T.H. James, The Theory of The Photographic Process, 4th Edition, Chapter 3, US Patent Nos.
  • the single jet method in which a silver nitrate solution is added in a halide and gelatin solution has been long used for manufacturing photographic emulsion.
  • the formed silver halide grains are a mixture of different kinds of shapes and sizes.
  • the shape and size of the formed silver halide grains can be controlled by the kind and concentration of the solvent existing in the gelatin solution and by the addition speed.
  • the presence of bromide in excess can promote the formation of octahedral grains, predominantly bounded by [111] crystal face, while a lower quantity of bromide promotes the formation of cubic grains having [100] crystal face.
  • An intermediate quantity of bromide and the presence of a silver halide solvent in particular during Ostwald ripening, promote the formation of tetradecahedral or spherical grains, having both [100] and [111] crystal faces.
  • composition of silver halide grains influences the shape of the grain.
  • Silver bromo-iodide grains have a higher inclination to form [111] crystal faces than silver bromide.
  • Silver chloride principally forms [100] faces in any condition and it is difficult to form [111] crystal faces.
  • a double jet precipitation technique at pAg between 8 and 9 and in presence of a solvent of silver halide such as thiourea, ammonia or thioether.
  • a solvent of silver halide such as thiourea, ammonia or thioether.
  • increasing pAg promotes the formation of a higher ratio of [111] faces to [100] faces.
  • the pAg is maintained at the lowest value within said range to form almost perfect cubes. In this condition rounded cube grains predominantly bounded by [100] crystal face and having at least one, and at most eight [111] crystal faces are normally formed.
  • the dispersing medium in the reaction vessel is initially substantially free of iodide ions, i.e., lower than 0.5%M, since the presence of iodide prior to concurrent introduction of silver and halide salts favors the formation of thick non-tabular grains.
  • the pBr of the reaction vessel is initially maintained between 0.6 and 1.6.
  • Tabular grain emulsions can be defined as intermediate and high aspect ratio tabular grain emulsions.
  • the term "high aspect ratio” is defined as requiring that the silver halide grains having a thickness of 0.3 ⁇ m or less and a diameter of at least 0.6 ⁇ m have an average aspect ratio of at least 8:1 and account for at least 50% of the total projected area of the silver halide grains present in the emulsion.
  • the term is thus defined in conformity with the term used in the patents relating to tabular grain emulsions cited above.
  • intermediate aspect ratio as applied to tabular grain emulsions is defined as requiring that the tabular silver halide grains having a thickness of 0.3 ⁇ m or less and a diameter of at least 0.6 ⁇ m have an average aspect ratio in the range of from 5:1 to 8:1 and account for at least 50% of the total projected area of the silver halide grains present in the emulsion.
  • thin intermediate aspect ratio is similarly defined, except that the reference thickness of 0.3 ⁇ m is replaced by a reference thickness of 0.2 ⁇ m.
  • the grain characteristics described above of the tabular silver halide grains can be readily ascertained by procedures well known to those skilled in the art.
  • the term "diameter” is defined as the diameter of a circle having an area equal to the projected area of the grain.
  • the term “thickness” means the distance between the two substantially parallel main planes constituting the tabular silver halide grains. From the measure of diameter and thickness of each grain the diameter:thickness of each grain can be calculated, and the diameter to thickness ratios of all tabular grains can be averaged to obtain their average diameter:thickness ratio.
  • the average diameter to thickness ratio is the average of individual tabular grain diameter:thickness ratios. In practice it is simpler to obtain an average diameter and an average thickness of the tabular grains and to calculate the average diameter:thickness ratio as the ratio of these two averages. Whatever the used method may be, the average diameter:thickness ratios obtained do not significantly differ.
  • the host tabular silver halide grains contained in the silver halide emulsion of this invention have preferably an average aspect ratio of at least 3:1, preferably at least 5:1, more preferably of from 5:1 to 8:1.
  • Average diameters of the tabular silver halide grains suitable for use in this invention range from about 0.3 to about 5 ⁇ m, preferably 0.5 to 3 ⁇ m, more preferably 0.8 to 1.5 ⁇ m.
  • the tabular silver halide grains suitable for use in this invention have a thickness of less than 0.4 ⁇ m, preferably less than 0.3 ⁇ m and more preferably less than 0.2 ⁇ m.
  • the dispersing medium for said silver halide grains can be chosen among those conventionally employed in the silver halide emulsions.
  • Preferred dispersion media include hydrophilic colloids, such as proteins, protein derivatives, cellulose derivatives (e.g. cellulose esters), gelatin (e.g. acid or alkali treated gelatin), gelatin derivatives (e.g. acetylated gelatin, phthalated gelatin and the like), polysaccharides (e.g. dextran), gum arabic, casein and the like.
  • hydrophilic colloids in combination with synthetic polymeric binders and peptizers such as acrylamide and methacrylamide polymers, polymers of alkyl and sulfoalkyl acrylates and methacrylates, polyvinyl alcohol and its derivatives, polyvinyl lactams, polyamides, polyamines, polyvinyl acetates, and the like.
  • synthetic polymeric binders and peptizers such as acrylamide and methacrylamide polymers, polymers of alkyl and sulfoalkyl acrylates and methacrylates, polyvinyl alcohol and its derivatives, polyvinyl lactams, polyamides, polyamines, polyvinyl acetates, and the like.
  • water soluble salts are removed from the emulsion by procedures known in the art.
  • Suitable cleaning arrangements are those wherein the dispersing medium and soluble salts dissolved therein can be removed from the silver halide emulsion on a continuous basis, such as, for example, a combination of dialysis or electrodialysis for the removal of soluble salts or a combination of osmosis or reverse osmosis for the removal of the dispersing medium.
  • ultrafiltration is a particularly advantageous cleaning arrangement for the practice of this process.
  • an ultrafiltration unit comprising membranes of inert, non-ionic polymers is used as a cleaning arrangement. Since silver halide grains are large in comparison with the dispersing medium and the soluble salts or ions, silver halide grains are retained by said membranes while the dispersing medium and the soluble salts dissolved therein are removed.
  • the action mechanism of preferred membranes is described in GB 1,307,331.
  • the membranes used in the ultrafiltration comprise a very thin layer of extremely fine pore texture supported upon a thicker porous structure.
  • Suitable membranes consist of polymers such as polyvinylacetate, polyvinylalcohol, polyvinylformate, polyvinylethers, polyamides, polyimides, polyvinyl chloride and polyvinylidene chloride, aromatic polymers, such as aromatic polyesters, polytetrafluoroethylene, regenerated cellulose, cellulose esters, such as cellulose acetate, or mixed cellulose esters.
  • the membranes in question have anisotropic, semipermeable properties, show considerable mechanical, thermal and chemical stability and are photographically inert.
  • the membranes are preferably permeable to molecules having molecular weights of up to about 300,000 and, more especially, of up to about 50,000.
  • the novel silver halide grain emulsion of the present invention is obtained by a precipitation method by adding an aqueous solution of a halide and silver to the host silver halide grain emulsion above described, under controlled conditions of pAg, pH and temperature.
  • a first addition of silver and/or halide salt solution was performed until to reach a pAg between 7 and 9, preferably between 7.5 and 8.5.
  • Said first addition can be performed by a single jet of silver salt solution, such as AgNO 3 , and/or a single yet of halide salt solution, such as NaCl, KI, KBr, and the like. A pause between the two additions can be performed.
  • silver and halide salt solutions may be concurrently added by a double jet method.
  • two different halide salts are concurrently or sequentially added.
  • chloride and bromide salts or chloride and iodide salts are concurrently or sequentially added.
  • a total of Ag between 1 and 20 mmoles, preferably between 4 and 10 mmoles per mole of Ag of the starting emulsion was consumed.
  • a double jet of silver and halide salt solutions was performed, adding from 0.01 to 0.10, preferably from 0.03 to 0.07 moles of Ag per mole of Ag of the starting emulsion.
  • Said addition can be performed by accelerated or constant flow rate, the latter being however preferred.
  • said halide salts consist of chloride and/or bromide salts.
  • Said isothiouronium compound is represented by the following formula: wherein R1 and R2 are straight or branched alkyl group, alkylene group, aryl group having from 1 to 10 carbon atoms, or allyl group, with at least one of R 1 and R 2 being an allyl group, A is a divalent organic linking group such as, for example, straight or branched divalent alkyl group, alkylene group, or aralkyl group having from 1 to 14 carbon atoms, and R 3 is a moiety selected in the class of carboxyl moiety, sulfo moiety, hydroxyl moiety, or amino moiety, B is an anion, and n is 0 (when R 3 is a negatively charged group) or 1 (when R 3 is a uncharged group).
  • alkyl group is intended to include not only pure hydrocarbon alkyl chains such as methyl, ethyl, octyl, cyclo-hexyl, isooctyl, tert-butyl and the like, but also such alkyl chains bearing such conventional substituentes in the art such as hydroxyl, alkoxy, phenyl, halo (F, Cl, Br, I), cyano, nitro, amino, etc.
  • alkyl moiety on the other hand is limited to the inclusion of only pure hydrocarbon alkyl chains such as methyl, ethyl, propyl, cyclo-hexyl, isooctyl, tert-butyl, and the like.
  • Typical examples of said isothiouronium compounds are the following, being understood that the invention is not limited thereto.
  • a pause of from 1 to 60, preferably of from 5 to 40 minutes is performed between said first addition and said second double jet addition.
  • the pAg can be adjusted in the range between 8 and 9.
  • the silver halide grain emulsion of the present invention is chemically sensitized using the usual sensitizing agents. Sulfur containing compounds, gold and noble metal compounds, polyoxylakylene compounds are particularly suitable.
  • the silver halide emulsions may be chemically sensitized with a sulfur sensitizer, such as allyl-thiocarbamide, thiourea, cystine, etc.; an active or inert selenium sensitizer; a reducing sensitizer such as stannous salt, a polyamine, etc.; a noble metal sensitizer, such as gold sensitizer, more specifically potassium aurithiocyanate, potassium chloroaurate, etc.; or a sensitizer of a water soluble salt such as for instance of ruthenium, rhodium, iridium and the like, more specifically, ammonium chloropalladate, potassium chloroplatinate and sodium chloropalladite, etc.; each being employed either alone or in a suitable combination.
  • a sulfur sensitizer such as allyl-thiocarbamide, thiourea, cystine, etc.
  • an active or inert selenium sensitizer such as stannous salt, a polyamine,
  • the silver halide grain emulsion of the present invention may be optically sensitized to a desired region of the visible spectrum.
  • the method for spectral sensitization of the present invention is not particularly limited.
  • optical sensitization may be possible by using an optical sensitizer, including a cyanine dye, a merocyanine dye, complex cyanine and merocyanine dyes, oxonol dyes, hemioxonol dyes, styryl dyes and streptocyanine dyes, either alone or in combination.
  • Particularly useful optical sensitizers are the dyes of the benzoxazole-, benzimidazole- and benzothiazole-carbocyanine type.
  • the addition of the spectral sensitizer can be performed before or after said double jet addition of silver and halide salts.
  • said spectral sensitizers produce J aggregates if adsorbed on the surface of the silver halide grains and a sharp absorption band (J-band) with a bathochromic shifting with respect to the absorption maximum of the free dye in aqueous solution.
  • J-band absorption band
  • Spectral sensitizing dyes producing J aggregates are well known in the art, as illustrated by F. M. Hamer, Cyanine Dyes and Related Compounds , John Wiley and Sons, 1964, Chapter XVII and by T. H. James, The Theory of the Photographic Process, 4th edition, Macmillan, 1977, Chapter 8.
  • J-band exhibiting dyes are cyanine dyes.
  • Such dyes comprise two basic heterocyclic nuclei joined by a linkage of methine groups.
  • the heterocyclic nuclei preferably include fused benzene rings to enhance J aggregation.
  • the heterocyclic nuclei are preferably quinolinium, benzoxazolium, benzothiazolium, benzoselenazolium, benzimidazolium, naphthoxazolium, naphthothiazolium and naphthoselenazolium quaternary salts.
  • the silver halide emulsion of the present invention is ripened at a temperature between 30° and 60°C, preferably between 30° and 50°C.
  • additives conveniently used depending upon their purpose.
  • additives include, for example, stabilizers or antifoggants such as azaindenes, triazoles, tetrazoles, imidazolium salts, polyhydroxy compounds and others; film hardeners such as aldehyde, aziridine, isoxazole, vinylsulfone, acryloyl, triazine type, etc.; developing promoters such as benzyl alcohol, polyoxyethylene type compounds, etc.; image stabilizers such as compounds of the chromane, cumaran, bisphenol type, etc.; and lubricants such as wax, higher fatty acids glycerides, higher alcohol esters of higher fatty acids, etc.
  • stabilizers or antifoggants such as azaindenes, triazoles, tetrazoles, imidazolium salts, polyhydroxy compounds and others
  • film hardeners such as aldehyde, aziridine, isoxazole, vinylsul
  • coating aids modifiers of the permeability in the processing liquids, defoaming agents, antistatic agents and matting agents may be used.
  • Other useful additives are disclosed in Research Disclosure, Item 17643, December 1978 in Research Disclosure, Item 18431, August 1979 and in Research Disclosure 308119, Section IV, 1989.
  • the resulting silver halide grains shown, to electron microscope, a grain structure modification if compared with the starting silver halide grains.
  • an etching of grains has taken place with the formation of cracked or hollow zones, around which, silver halide protrusions form crater or hopper structures on the surface of grain.
  • a grain analysis by X-ray difractometry showed that these protrusions are predominantly formed by a silver halide composition equal to that of the second double jet addition.
  • cracked zone defines a zone of the grain surface on which the process of the present invention makes an irregular furrow or groove on a surface of the grain. Said furrow is due to the etching of the grain surface with attendant dissolution of part of the silver halide present on the surface of the host grain.
  • These "cracked zones” can be then defined as narrow and long depressions, that generally appear on only a small part of one grain surface.
  • the term “hollow zone” defines a zone of the grain surface on which the process of the present invention make a concavity such as the hollow of one's hand. In this case “hollow” does not mean a cavity passing through the grain.
  • the term “hollow zone” defines a large and rounded depression that appears on the major part of one grain surface. This is different from the feature defined by the term “cracked zone”.
  • crater structure defines a structure comprising a cracked zone, as previously defined, having additional protrusions that form a raised area around the edges of said cracked zone. Said crater structure, and in particular said additional protrusions are due to the deposition of silver halide added during the process of the present invention.
  • hopper structure defines a structure comprising a hollow zone, as previously defined, having additional protrusions growing on the edges or corners of the grain, in such a way that a stronger marked depression is formed.
  • Hopper development of crystal is a well known phenomenon in the art of crystallography. Hopper development takes place when a growing gradient of supersaturation from the center to the edges of the crystal face promotes a higher rate of nucleation near the edges of the crystal face and a lower one around the center. This leads to a preferential thickening at the periphery, more pronounced starvation of the face center, and thus to a hopper structure, either in the form of shallow disc or as hollow prism. References can be found in J.J.Gilman, The Art and Science of Growing Crystals, pp. 141-143 John Wiley & Sons, Inc., New York - London, 1963.
  • the mechanism of formation of the crater structures of the present invention is not yet completely understood. It may be explained as a particular hopper development that takes place on a limited part of the crystal face, when a little gradient of supersaturation is created from the center to the edges of said cracked zones. The preferential thickening is then limited to the edges of said cracked zone, with a more pronounced starvation of its hollow center.
  • said grain structure modification need not necessarily be present on all the silver halide grains of the silver halide emulsion obtained with the method of the present invention.
  • the result of better sensitometric characteristics provided by the method of the present invention can be already obtained when at least 1%, preferably at least 5%, more preferably at least 10% by number of grains of the silver halide grain emulsion of the present invention show said grain structure modification.
  • the resulting silver halide grains have at least one protrusion on at least one of said [111] crystal faces.
  • [100] crystal faces are etched with the formation of cracked or hollow zones.
  • the resulting silver halide grains when we start from silver bromide and/or silver bromo-iodide up to 8%M of iodide host grains having a tabular shape predominantly bounded by two [111] main crystal faces and an aspect ratio between 5:1 and 8:1, the resulting silver halide grains have at least one protrusion on at least one of said [111] crystal faces, said protrusions being formed around the edges of at least one cracked zone and forming at least one crater structure on said crystal face.
  • a light-sensitive silver halide photographic material can be prepared by coating the above described silver halide emulsion of the present invention on a photographic support.
  • a photographic support There is no limitation with respect to the support.
  • materials suitable for the preparation of the support include glass, paper, polyethylene-coated paper, metals, cellulose nitrate, cellulose acetate, polystyrene, polyesters such as polyethylene terephthalate, polyethylene, polypropylene and other well known supports.
  • Said light-sensitive silver halide photographic material specifically is applicable to light-sensitive photographic color materials such as color negative films, color reversal films, color papers, etc., as well as black-and-white light-sensitive photographic materials such as X-ray light-sensitve materials, lithographic light-sensitive materials, black-and-white photographic printing papers, black-and-white negative films, etc.
  • Preferred light-sensitive silver halide photographic materials are X-ray light-sensitive materials comprising the above described silver halide emulsion coated on one surface, preferably on both surfaces of a support, preferably a polyethylene terephthalate support.
  • the silver halide emulsion is coated on the support at a total silver coverage comprised in the range of 3 to 6 grams per square meter.
  • the X-ray light-sensitive materials are associated with intensifying screens so as to be exposed to radiation emitted by said screens.
  • the screens are made of relatively thick phosphor layers which transform the X-rays into light radiation (e.g., visible light).
  • the screens absorb a portion of X-rays much larger than the light-sensitive material and are used to reduce the X-ray dose necessary to obtain a useful image.
  • the phosphors can emit radiation in the blue, green or red region of the visible spectrum and the silver halide emulsions are sensitized to the wavelength region of the light emitted by the screens. Sensitization is performed by using spectral sensitizing dyes adsorbed on the surface of the silver halide grains as known in the art.
  • the exposed light-sensitive materials of this invention can be processed by any of the conventional processing techniques.
  • the processing can be a black-and-white photographic processing for forming a silver image or a color photographic processing for forming a dye image depending upon the purpose.
  • Such processing techniques are illustrated for example in Research Disclosure, 17643, December 1978.
  • Roller transport processing in an automatic processor is particularly preferred, as illustrated in US Pat. Nos. 3,025,779, 3,515,556, 3,545,971 and 3,647,459 and in UK Pat. No. 1,269,268.
  • Hardening development can be undertaken, as illustrated in US Pat. No. 3,232,761.
  • Emulsions 1 and 2 were coated double side with conventional coating methods for a total of 4.4 g of Ag/square meter, incubated 15h at 50°C, and exposed to blue and green light and to X-rays with 3M TRIMAXTM T8 intensifying screen, and processed in a 3M TRIMATICTM XP507 automatic processor using a 3M XAD/2 Developer and a 3M XAF/2 Fixer.
  • emulsion 1 shows a modified grain structure when compared to the starting emulsion.
  • emulsion 1 shows a sharper corner profile than the starting emulsion with the presence of marked hollow zone bounded from protrusions that form a typical hopper structure on at least one crystal face of the grain.
  • a silver bromide emulsion comprising silver bromide tabular grain having an aspect ratio of 8:1 was added per mole of Ag and at pH 5.7, 5.6 ml of NaCl 4.27N and 6 mmoles of Ag, employing a solution of AgNO 3 0.25N, to have pAg 8.0, 56ml of KI 0.06N and 77 ml of a 1.0% by weight solution of optical sensitizer having the following formula:
  • a double jet addition of NaCl and AgNO 3 solution was performed for 60 minutes to precipitate 6M% of AgCl per mole of Ag. During said double jet addition the pAg was mantained to 8.0 and pH to 6.7.
  • Emulsions 1 and 2 were coated and treated as for example 1. In the following table 2 the photographic characteristics of the two emulsions are reported. Fog Dmax Average Contrast Speed Blue Green Em. 1 (inv.) 0.21 2.6 1.59 3.13 2.95 Em. 2 (comp.) 0.20 2.4 1.56 2.77 2.59
  • emulsion 1 shows a modified grain structure when compared to the starting emulsion. Protrusions that form crater structures around the edges of cracked zones are evident on main faces.
  • a mean diameter of 0.7 ⁇ m and comprising 97.74M% of AgBr and 2.26M% of AgI was added per mole of Ag at pH 5.8, pAg 8.5, and at a temperature of 40°C, 6 ml of NaCl 4.27N, 68 ml of a 1% by weight solution of optical sensitizer having the following formula: and, after a pause of 30 minutes, 5 mmoles of Ag in 15 minutes, employing a solution of AgNO 3 0.25N until a pAg of 8.0 was obtained.
  • emulsion 1 The same conditions of emulsion 1 were used except the use, during the double jet addition, of 8.1ml of a 0.1% by weight solution of the same isothiouronium salt of example 1, instead of benzothiazolium and a lower quantity of the solution of sodium p-toluenethiosulfonate (6.95ml per mole of Ag). The resulting emulsion was ripened for 120 minutes at 45°C and pAg 8.2.
  • Emulsions 1, 2 and 3 were coated and treated as for example 1.
  • Fog Dmax Average Contrast Blue Speed Green Speed X-ray Speed Em. 1 (comp.) 0.16 3.55 2.53 2.26 2.57 2.68 Em. 2 (inv.) 0.17 3.61 2.67 2.31 2.62 2.75 Em. 3 (comp.) 0.17 3.70 2.81 2.23 2.47 2.63
  • emulsions 1 and 2 show a modified grain structure.
  • emulsions 1 and 2 show a sharper corner profile than the starting emulsion with the presence of marked hollow zone bounded from protrusions that form a tipical hopper structure on at least one crystal face of the grain.
  • emulsion 2 of example 3 The same conditions of emulsion 2 of example 3 were used except the use, during the double jet addition, of 0.3 mg of thiosulfate, 0.5 mg of NaAuCl 4 and 9 mg of KCNS per mole of silver. At the end the emulsion was ripened for 60 minutes at 45°C, for 75 minutes at 55°C, for 35 minutes at 60°C.
  • emulsion 2 The same conditions of emulsion 2 were used, but the use of KCNS. At the end the emulsion was ripened for 60 minutes at 45°C, for 75 minutes at 55°C, for 60 minutes at 60°C.
  • Emulsion 1 shows the same hopper structure, showing edge and corner protrusions bounding strong marked hollow zones, as in the previous example 3.
  • the absence of optical sensitizer does not affect sensitometric results (+0.13 X-ray speed, +0.14 and +0.10 respectively for blue and green speed).
  • Emulsion 1 91 minutes Emulsion 2 95 minutes
  • both emulsions were stabilized in conventional manner, mantained 10 minutes at 53°C, and then cooled and stored.
  • Emulsions 1, 2 and 3 were coated and treated as for example 1. The results are summarized in the following table 6.
  • Fog Dmax Average Contrast Blue Speed Green Speed X-ray Speed Em. 1 (inv.) 0.21 3.52 2.32 2.35 2.74 2.95 Em. 2 (inv.) 0.21 3.54 2.31 2.36 2.74 2.95 Em. 3 (comp.) 0.23 3.57 2.50 2.04 2.46 2.61
  • Emulsions 1, 2 and 3 were coated and treated as for example 1. The results are summarized in the following table 7.
  • Fog Dmax Average Contrast Blue Speed Green Speed X-ray Speed Em. 1 (comp.) 0.22 3.50 1.85 1.56 1.92 1.93 Em. 2 (inv.) 0.18 3.61 2.40 2.15 2.47 2.58 Em. 3 (comp.) 0.20 3.75 2.66 1.97 2.40 2.48
  • a silver bromide emulsion comprising silver bromide tabular grain having an aspect ratio of 8:1 and a mean diameter of about 1.10 ⁇ m was added per mole of Ag, at pH 5.8 and at 40°C, a KBr solution until to have pAg 8.9, 1 mmoles of Ag, employing a solution of AgNO 3 0.25N, to have pAg 8.0. Then a double jet of 53ml of KI 0.06N and AgNO 3 0.25N until to use 4 mmoles of Ag and, after a pause to correct the pAg to 8.5, 60 ml of a 1% by weight solution of an optical sensitizer having the following formula:
  • Emulsions 1 and 2 were coated and treated as for example 1. The results are summarized in the following table 8.
  • Fog Dmax Average Contrast Blue Speed Green Speed X-ray Speed Em. 1 (inv.) 0.20 3.80 2.55 2.29 2.69 2.85 Em. 2 (comp.) 0.21 3.90 2.64 1.98 2.41 2.50
  • emulsion 2 shows a sligthly modified surface of the grains when compared with the starting emulsion. In particular only few grains show protrusions that form crater structures around the edges of cracked zones on main faces.

Claims (19)

  1. Procédé de préparation d'une émulsion photographique d'halogénure d'argent comprenant des grains d'halogénure d'argent creux ou fissurés sensibilisés chimiquement et spectralement ayant une structure en cratère ou entonnoir, ledit procédé comprenant les étapes suivantes :
    (a) la formation dans un récipient réactionnel d'une émulsion de grains d'halogénure d'argent hôtes, laquelle émulsion comprend, dans un milieu dispersant colloïdal hydrophile, des grains d'halogénure d'argent contenant au moins 50 moles % de bromure d'argent et comportant une structure cristalline cubique comprenant au moins une face cristalline [111] et/ou au moins une face cristalline [100];
    (b) la réalisation, à un pH de 5 à 7 et à une température entre 30° et 50°C, d'une première addition de solutions de sels d'argent et/ou d'halogénure jusqu'à ce qu'un pAg de 7 à 9 soit atteint;
    (c) la réalisation, à pAg de 7 à 9, d'une seconde addition de solutions de sels d'argent et d'halogénure, jusqu'à ce que de 0,01 à 0,10 mole d'argent par mole d'argent de l'émulsion d'halogénure d'argent hôte ait été ajoutée, tout en versant en même temps dans le récipient de réaction une solution comprenant un composé d'isothiouronium ayant la formule suivante :
    Figure 00420001
    dans laquelle R1 et R2 représentent un groupe alkyle droit ou ramifié, un groupe alkylène, un groupe aryle ou un groupe allyle, au moins un des R1 et R2 représentant un groupe allyle, A est un groupe de liaison organique divalent et R3 est un fragment choisi dans la classe comprenant le fragment carboxyle, le fragment sulfo, le fragment hydroxyle et le fragment amino, B est un anion et n est égal à 0 (lorsque R3 est un groupe chargé négativement) ou 1 (lorsque R3 est un groupe non chargé), et
    d) la maturation, à pH de 6 à 8, pAg de 7 à 9 et à une température entre 30° et 50°C, de l'émulsion d'halogénure d'argent obtenue.
  2. Procédé suivant la revendication 1, caractérisé en ce que l'émulsion d'halogénure d'argent hôte comprend des grains d'halogénure d'argent contenant au moins 80 moles % de bromure, la partie restante contenant moins de 20 moles % d'iodure.
  3. Procédé suivant la revendication 1, caractérisé en ce que l'émulsion d'halogénure d'argent hôte comprend des grains de bromure d'argent.
  4. Procédé suivant la revendication 1, caractérisé en ce que l'émulsion d'halogénure d'argent hôte comprend, dans un milieu dispersant colloïdal hydrophile, des grains d'halogénure d'argent sphériques ou tétradécaédriques contenant au moins 50 moles % de bromure et comportant au moins une, tout au plus huit faces cristallines [111].
  5. Procédé suivant la revendication 4, caractérisé en ce que les grains d'halogénure d'argent contiennent au moins 80 moles % de bromure d'argent, la partie restante contenant moins de 20 moles % d'iodure.
  6. Procédé suivant la revendication 1, caractérisé en ce que l'émulsion d'halogénure d'argent hôte comprend, dans un milieu dispersant colloïdal hydrophile, des grains tabulaires contenant au moins 50 moles % de bromure et principalement liés par des faces cristallines [111].
  7. Procédé suivant la revendication 6, caractérisé en ce que les grains tabulaires d'halogénure d'argent hôtes ont un rapport d'aspect plus élevé que 3/1.
  8. Procédé suivant la revendication 6, caractérisé en ce que les grains tabulaires d'halogénure d'argent hôtes sont des grains de bromure d'argent.
  9. Procédé suivant la revendication 1, caractérisé en ce que la première addition est réalisée avec des solutions de sels d'argent et de chlorure et/ou de bromure.
  10. Procédé suivant la revendication 1, caractérisé en ce que la première addition est réalisée avec des solutions de sels d'argent et de chlorure et/ou d'iodure.
  11. Procédé suivant la revendication 1, caractérisé en ce qu'une pause est réalisée entre la première addition des solutions de sel d'argent et de sel d'halogénure.
  12. Procédé suivant la revendication 1, caractérisé en ce que le composé d'iosothiouronium est ajouté 2 à 15 minutes après le commencement de la seconde addition de sels d'argent et d'halogénure.
  13. Procédé suivant la revendication 1, caractérisé en ce que l'émulsion résultante est sensibilisée chimiquement et spectralement.
  14. Procédé suivant la revendication 1, caractérisé en ce qu'un colorant de sensibilisation spectrale est ajouté avant ou après la seconde addition de sels d'argent et d'halogénure.
  15. Procédé suivant la revendication 14, caractérisé en ce que le colorant de sensibilisation spectrale est un colorant de cyanine ou mérocyanine formant des agrégats J.
  16. Procédé suivant la revendication 1, caractérisé en ce que la seconde addition est réalisée avec des solutions de sels d'argent et de chlorure, de bromure ou de chlorobromure.
  17. Emulsion photographique d'halogénure d'argent comprenant des grains d'halogénure d'argent sensibilisés chimiquement et spectralement, caractérisée en ce que les grains d'halogénure d'argent sont des grains sphériques ou tétradécaédriques liés par six faces cristallines [100] et comprenant au moins une, tout au plus huit faces cristallines [111], au moins une desdites faces cristallines [100] comportant au moins une zone fissurée ou creuse et au moins une desdites faces cristallines [111] comportant des saillies d'halogénure d'argent formant autour de ladite zone creuse ou fissurée au moins une structure en cratère ou entonnoir sur au moins une de ces faces cristallines [100] des grains d'halogénure d'argent précités.
  18. Emulsion photographique d'halogénure d'argent comprenant des grains d'halogénure d'argent sensibilisés chimiquement et spectralement, caractérisée en ce que les grains d'halogénure d'argent sont des grains tabulaires liés principalement par des faces cristallines [111], au moins une desdites faces cristallines [111] comportant au moins une zone fissurée ou creuse et des saillies d'halogénure d'argent formant autour de ladite zone creuse ou fissurée au moins une structure en cratère ou entonnoir sur au moins une desdites faces cristallines [111] des grains d'halogénure d'argent précités.
  19. Emulsion photographique d'halogénure d'argent suivant l'une ou l'autre des revendications 17 et 18, caractérisée en ce que les grains d'halogénure d'argent sont composés d'au moins 80 moles % de bromure d'argent, la partie restante contenant moins de 20 moles % d'iodure d'argent et les saillies d'halogénure d'argent précitées sont composées d'au moins 80 moles % de chlorure d'argent et/ou de bromure d'argent.
EP92111247A 1991-07-15 1992-07-02 Emulsion à l'halogénure d'argent comprenant des grains ayant une structure en forme de cratère ou d'entonnoir et procédé de fabrication d'une telle émulsion Expired - Lifetime EP0523464B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITMI911957 1991-07-15
ITMI911957A IT1251792B (it) 1991-07-15 1991-07-15 Emulsione agli alogenuri d'argento comprendente granuli aventi struttura a cratere o a tramoggia e metodo per la sua preparazione.

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EP0523464A1 EP0523464A1 (fr) 1993-01-20
EP0523464B1 true EP0523464B1 (fr) 1998-01-14

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US5541053A (en) * 1993-10-20 1996-07-30 Eastman Kodak Company Process for the preparation of silver halide photographic emulsions containing grains having (100) faces with cavities and photographic emulsions so prepared
FR2711431B1 (fr) * 1993-10-20 1996-01-05 Kodak Pathe Emulsion d'halogénure d'argent photographique comprenant des grains à faces (100) avec des cavités.

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US4503139A (en) * 1983-05-09 1985-03-05 Polaroid Corporation Photographic products and processes and novel compounds
EP0226184A3 (fr) * 1985-12-19 1988-11-09 EASTMAN KODAK COMPANY (a New Jersey corporation) Agent de contrôle pour le développement de germes dans des matériaux et procédés photographiques
JPH0820690B2 (ja) * 1986-02-03 1996-03-04 コニカ株式会社 ハロゲン化銀粒子及び核ハロゲン化銀粒子を含む写真感光材料
JP2631720B2 (ja) * 1988-10-31 1997-07-16 コニカ株式会社 ハロゲン化銀結晶粒子及びハロゲン化銀感光材料

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IT1251792B (it) 1995-05-26
ITMI911957A0 (it) 1991-07-15
ITMI911957A1 (it) 1993-01-15
JPH05216149A (ja) 1993-08-27
EP0523464A1 (fr) 1993-01-20
DE69224018D1 (de) 1998-02-19

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