EP0911687B1 - Procédé pour la préparation des crystaux tabulaires (111) riches en bromure d'argent et morphologiquement homogènes - Google Patents

Procédé pour la préparation des crystaux tabulaires (111) riches en bromure d'argent et morphologiquement homogènes Download PDF

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Publication number
EP0911687B1
EP0911687B1 EP19970203313 EP97203313A EP0911687B1 EP 0911687 B1 EP0911687 B1 EP 0911687B1 EP 19970203313 EP19970203313 EP 19970203313 EP 97203313 A EP97203313 A EP 97203313A EP 0911687 B1 EP0911687 B1 EP 0911687B1
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EP
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Prior art keywords
silver
gelatin
grains
emulsion
tabular
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German (de)
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EP0911687A1 (fr
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Kathy c/o Agfa-Gevaert N.V. Elst
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Agfa Gevaert NV
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Agfa Gevaert NV
Agfa Gevaert AG
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Priority to DE69729869T priority Critical patent/DE69729869T2/de
Priority to EP19970203313 priority patent/EP0911687B1/fr
Priority to US09/168,986 priority patent/US6087085A/en
Priority to JP30107298A priority patent/JPH11223894A/ja
Publication of EP0911687A1 publication Critical patent/EP0911687A1/fr
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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
    • G03C1/0051—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
    • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
    • G03C5/16—X-ray, infrared, or ultraviolet ray processes

Definitions

  • the present invention relates to a method for preparing homogeneously divided substantially hexagonal (111) tabular grains rich in silver bromide.
  • Tabular silver halide grains are grains possessing two parallel crystal faces with a ratio between the diameter of a circle having the same area as these crystal faces, and thickness, being the distance between the two major faces, of two or more.
  • Tabular grains are known in the photographic art for quite some time. As early as 1961 Berry et al. described the preparation and growth of tabular silver bromoiodide grains in Photographic Science and Engineering, Vol 5, No 6. A discussion of tabular grains appeared in Duffin, Photographic Emulsion Chemistry, Focal Press, 1966, p. 66-72.
  • the anisotropic growth of the said tabular grains is known to be due to the formation of parallel twin planes in the nucleation step of the precipitation.
  • the shape of the tabular grains may be variable: triangular, hexagonal, disc-shaped, trapezoidal and even needle-shaped grains can be formed.
  • the said shape can be regular or irregular.
  • Emulsion preparation of tabular grains by means of the methods well-known by a person skilled in the art of photography leads to grain populations consisting of a mixture of all shapes of crystals described hereinbefore.
  • EP-A's 0 566 076; 0 506 947; 0 518 066 and 0 513 722 and US-A 4,797,354 are related with the preparation of monodisperse hexagonal tabular crystals.
  • said US-A 4,797,354 the preparation has been described of tabular emulsions having a high percentage of hexagonal, tabular crystals. accounting for from 70 to 100 % of the total projected area of the said crystals with an average aspect ratio of from 2.5/1 to 20/1.
  • a further object of the present invention is to prepare the said (111) tabular grains rich in silver bromide accounting for an amount by number of the total amount of grains as high as possible in order to make said tabular grains account for at least 70 % of the total projective area of all grains, showing high morphologic homogeneity in concentrated reaction vessels in order to improve the precipitation efficiency and to make the preparation process more economically and ecologically acceptable.
  • Concentrating by ultrafiltration the said reaction mixture volume in the reaction vessel during precipitation growth steps is applied at any momenc when said ultrafiltration is performed e.g. with an ultrafiltration flux equal to or higher than total flow rates of silver salt and halide salt solutions.
  • a gelatinous silver halide emulsion having (111) tabular silver bromide, silver bromoiodide, silver bromochloride or silver bromochloroiodide grains, wherein at least 70 % of the total projected area of all grains is provided by tabular (111) grains having a preferred average aspect ratio of more than 2:1 and an average thickness of from 0.05 to 0.30 ⁇ m, wherein a ratio by number of traversual amounts of hexagonal tabular grains to triangular tabular crystals present is more than 10:1
  • a dispersion medium containing gelatin having less than 30 ⁇ moles of methionine per gram is prepared in order to apply the method of the present invention: an increased number of (111) tabular grains rich in silver bromide in the total grain population is obtained if use is made in the preparation method of the so-called "oxidized gelatin", characterized by the presence in the said gelatin of amounts of methionine of less than 30 ⁇ moles per gram of gelatin as set forth in US-A 4,713,320 and in Research Disclosure 29945, published March 1989.
  • a preparation method of (111) tabular grain emulsions wherein in the grain growth process use is made of gelatin derivatives with chemically modified NH 2 -groups and wherein said gelatin has a specific methionine content has been described in EP-A 0 697 618.
  • Modification of the methionine content of a gelatinous dispersion medium by means of an oxidizer which should be added to the reaction vessel immediately before nucleation formation has been described in US-A 5,372,975, wherein seed grains are further added. Seed grains formed in the presence of an oxidizing agent have been described in JP-A 05-210187, in JP-A 06-003758 and in JP-A 06-003759.
  • a total amount of silver nitrate of less than 10 % by weight, and more preferably 0.5 % to 5.0 %, is added during the nucleation step which preferably consists of an approximately equimolecular simultaneous addition of silver nitrate and halide salts at a pBr of 1.0 to 2.0.
  • the rest of the silver nitrate and halide salts is added during one or more consecutive double jet growth step(s) after having added to said reaction vessel.
  • Gelatin added before and/or during the said growth can be oxidized gelatin, already defined hereinbefore, or non-oxidized gelatin having 30 or more ⁇ moles of methionine per gram so that the total amount of gelatin may contain per gram an average amount of higher than 30 ⁇ moles of methionine, and even up to about 80 moles per gram.
  • growing said silver halide crystal nuclei proceeds by precipitation of silver halide by means of double-jet precipitation of an aqueous silver nitrate solution and an aqueous solution comprising halide ions, wherein more than 90 % and more preferably up to 95 % by weight of the total amount of silver nitrate is consumed.
  • the different steps of the precipitation can be alternated by physical ripening steps or by so called “neutralization steps", during which the pAg value is changed to a value required in the next growth step by adding an amount of silver nitrate solution or a water soluble halide salt within a well-defined time of addition by means of the single-jet technique.
  • Alternative ways to regulate the pAg to the desired value before continuing the processing are diluting the emulsion present in the reaction vessel, diafiltration or ultrafiltration and even flocculation and washing procedures, the last techniques being preferred to concentrate the emulsion crystals in the reaction vessel. Any combination or any choice of the mentioned techniques may be applied thereto.
  • the ratio of the second growth step to the first growth step and the pBr in this second growth step is such that the tabular (111) grains rich in silver bromide at the end of the preparation according to the method of the present invention exhibit an average aspect ratio of at least 2:1, more preferably from 5:1 to 15:1, wherein tabular (111) grains rich in silver bromide account for at least 70 %, and more preferably at least 90 % of the total projected area of all grains.
  • tabular grains rich in silver bromide prepared according to the method of the present invention have an average thickness of from 0.05 to 0.30 ⁇ m and more preferably from 0.05 up to 0.20 ⁇ m and a coefficient of variation of the grain size distribution of tabular grains of less than 0.30 and more preferably between 0.10 and 0.20.
  • polyalkyleneoxides as in US-A's 5,252,442 and 5,147,771.
  • an increasing flow rate of silver and halide solutions is preferably applied, e.g. a linearly increasing flow rate.
  • the flow rate at the end is about 3 to 10 times greater then at the start of the growth step.
  • nuclei can be prepared in a separate vessel, whereas growth of the said nuclei may proceed in another vessel.
  • the present invention besides performing nuclation in a concentrated reaction vessel, it is of utmost importance to concentrate the reaction mixture volume obtained by ultrafiltration during the precipitation growth steps by applying during said ultrafiltration process an ultrafiltration flux equal to (as preferred in steady-state circumstances) or higher than total flow rates of silver salt and halide salt solutions, thereby concentrating silver halide formed in the said reaction vessel to at least 250 g, expressed as an equivalent amount of silver nitrate, per liter, preferably up to 300 g and even more preferred up to 450 g per liter.
  • a temporary lower ultrafiltration flux is required.
  • the practically applied ultrafiltration or membrane flux further is a function of the total operative surface of the membrane and the trans-membrane pressure.
  • the right choice of the membrane used in order to reach the desired volume of the reaction mixture in the reaction vessel is thus very important.
  • the ultrafiltration procedure is applied in a continuous way during the precipitation steps, but, if required, it can be interrupted for short periods as e.g. during physical ripening preferably no ultrafiltration is applied.
  • the total reaction mixture volume can be lowered during the precipitation.
  • the reaction mixture volume can be readjusted, e.g. kept constant by the application of an additional jet of water.
  • the ultrafiltration module is conceived in such a way that the total volume of the ultrafiltration module and of its connecting means, is lower than 1/3 of the total precipitation volume.
  • the circulation flux through the ultrafiltration module is preferably high enough, in order to achieve a delay time in the module of any liquid volume unit of lower than 60 seconds and, most preferably lower than 30 seconds. Even delay times as low as 10 seconds can be achieved.
  • a preferred ultrafiltration module for the practice of this invention is a ROMICON HF2-20-PM10, provided with a pump.
  • the flow rate of the silver ion jet during the growth step(s) is linearly increased to an end rate of 25 ml/min per 500 g of silver nitrate to be precipitated and a linearly increasing flux having an end rate of about 50 ml/min is applied.
  • a flux of about 200 ml/min can be established if required.
  • a gelatinous silver halide emulsion is thus prepared according to the method of the present invention, wherein said emulsion has silver bromide, silver bromoiodide, silver bromochloride or silver bromochloroiodide grains (wherein the halide present in the highest amount as expressed in mole % is called first), and wherein at least 70 % of the total projected area of all grains is provided by tabular ⁇ 111 ⁇ grains having an average aspect ratio of more than 2:1 and an average thickness of from 0.05 to 0.30 ⁇ m, wherein a ratio by number of hexagonal tabular grains to triangular tabular grains is more than 10:1, and more preferably more than 20:1.
  • Said silver halide is furthermore, according to the present invention, present in said emulsion in an amount per liter of at least 250 g, more preferred up to 300 g and even up to 450 g, wherein silver halide is expressed as an equivalent amount of silver nitrate.
  • gelatin differing from the initial amount of gelatin present in the reaction vessel and which is added after ending nucleation is added in an amount of more than 80 % by weight of the total amount of gelatin used, wherein said gelatin differing from said initial amount of gelatin contains methionine in an amount of more than 30 moles per gram.
  • silver silver bromoiodide or silver bromochloroiodide iodide ions are present in an amount of up to 3 mole % and in a preferred embodiment iodide ions are provided by means of an iodide releasing agent.
  • iodide releasing agents are e.g. EP-A's 0 563 701, 0 563 708, 0 561 415 and 0 651 284.
  • Preparation of silver bromo(chloro)iodide emulsion crystals can be achieved by mixing a soluble bromide or bromochloride mixture and a soluble iodide salt in one or more of the halide solutions up to the desired concentrations, expressed in mol %, required in each preparation step by double jet or by a triple jet technique by separate addition of an iodide containing aqueous solution. Due to the lower solubility of silver iodide in comparison with silver bromide, said iodide ions are able to displace bromide and chloride ions from the grain, a technique known in the art as conversion.
  • Iodide ions may also be incorporated into the silver halide crystal lattice by the addition of a previously prepared silver iodide micrate emulsion, composed of either pure silver iodide or mixed halide ultrafine crystals, but as has already set forth hereinbefore in a preferred embodiment iodide releasing agents are used, at least partially, e.g. in one or more conversion steps during or at the end of the precipitation. Even bromide releasing agents are not excluded in the precipitation steps according to the method of this invention.
  • Silver chloride if present as in silver bromochloride or silver bromochloroiodide emulsions, takes about 5 mole % up to 20 mole % in the composition of the silver halide grains rich in silver bromide.
  • Two or more types of tabular silver halide emulsions that have been prepared differently can be mixed for forming a photographic emulsion for use in photographic materials according to the present invention, depending on the desired specifications.
  • the size distribution of the ⁇ 111 ⁇ tabular silver halide particles of the photographic emulsions prepared according to the method of the present invention is thus monodisperse as it is not desirable to have a low contrast, especially in the higher densities of the sensitometric curve, characteristic for heterodisperse emulsions with a coefficient of variation of the tabular grains between 0.20-0.40 which show a lower covering power.
  • a higher covering power is preferred, in order to coat less silver in the emulsion layers of suitable silver halide photographic materials and therefore the more homodisperse emulsions, prepared according to the method of the present invention are preferred with coefficients of variation being lower than 0.20 and more preferred from 0.10 to less than 0.20.
  • Tabular silver halide emulsions rich in silver bromide can be chemically sensitized as has been described e.g. in "Chimie et Physique Photographique” by P. Glafkides, in “Photographic Emulsion Chemistry” by G.F. Duffin, in “Making and Coating Photographic Emulsion” by V.L. Zelikman et al, and in "Die Grundlagen der Photographischen mit Silberhalogeniden” edited by H. Frieser and published by Akademische Verlagsgesellschaft (1968). Chemical sensitization has e.g. also been described in Research Disclosure N° 38957 (September 1996), Chapter IV.
  • chemical sensitization can be carried out by effecting the ripening in the presence of small amounts of compounds containing sulphur e.g. thiosulphate, thiocyanate, thioureas, sulphites, mercapto compounds, and rhodamines.
  • Said compounds containing sulphur can also be, at least partially, replaced by compounds containing selenium and/or tellurium.
  • the emulsions may be sensitized also by means of gold-sulphur, gold-sulphur-selenium, gold-selenium ripeners or by means of reductors as e.g. tin compounds described in GB-Patent 789,823, amines, hydrazine derivatives, formamidine-sulphinic acids, and silane compounds.
  • the tabular silver halide emulsions may be spectrally sensitized with methine dyes such as those described by F.M. Hamer in "The Cyanine Dyes and Related Compounds", 1964, John Wiley & Sons and in Research Disclosure N° 38957 (1994), Chapter V.
  • Dyes that can be used for the purpose of spectral sensitization include cyanine dyes, merocyanine dyes, complex cyanine dyes, complex merocyanine dyes, hemicyanine dyes, styryl dyes and hemioxonol dyes.
  • Particularly valuable dyes are those belonging to the cyanine dyes, merocyanine dyes and complex merocyanine dyes.
  • Oxacarbocyanines have been described e.g. in US-A 5,434,042.
  • Especially preferred green sensitizers in connection with the present invention are anhydro-5,5'-dichloro-3,3'-bis(n.sulfobutyl)-9-ethyloxacarbo-cyanine hydroxide and anhydro-5,5'-dichloro-3,3'-bis(n.sulfopropyl)-9-ethyl-oxacarbo-cyanine hydroxide.
  • Imidacarbocyanines as e.g.
  • spectral sensitization traditionally follows the completion of chemical sensitization. However, in connection with tabular grains, it is specifically considered that spectral sensitization may occur simultaneously with or may even precede completely the chemical sensitization step: the chemical sensitization after spectral sensitization is believed to occur at one or more ordered discrete sites of tabular grains.
  • emulsions prepared according to the present invention wherein the chemical sensitization proceeds in the presence of one or more phenidone and derivatives, a dihydroxy benzene as hydroquinone, resorcinol, catechol and/or a derivative(s) therefrom, one or more stabilizer(s) or antifoggant(s), one or more spectral sensitizer(s) or combinations of said ingredients.
  • a dihydroxy benzene as hydroquinone
  • resorcinol catechol and/or a derivative(s) therefrom
  • stabilizer(s) or antifoggant(s) one or more spectral sensitizer(s) or combinations of said ingredients.
  • 1-p-carboxyphenyl, 4,4' dimethyl-pyrazolidine-3-one may be added as a preferred auxiliary agent.
  • gelatinous silver halide emulsion rich in silver bromide of the present invention characterized by a specific gelatin composition as set forth hereinbefore is further coated in hydrophilic layer(s) which may, just as non-light-sensitive layers of the photographic material according to this invention, comprise compounds preventing the formation of fog or stabilizing the photographic characteristics during the production or storage of the photographic elements or during the photographic treatment thereof.
  • hydrophilic layer(s) may, just as non-light-sensitive layers of the photographic material according to this invention, comprise compounds preventing the formation of fog or stabilizing the photographic characteristics during the production or storage of the photographic elements or during the photographic treatment thereof.
  • Many known compounds can be added as fog-inhibiting agent or stabilizer to the silver halide emulsion layer or to other coating layers in water-permeable relationship therewith such as an undercoat or a protective layer. Suitable examples are e.g.
  • heterocyclic nitrogen-containing compounds such as benzothiazolium salts, nitroimidazoles, nitrobenzimidazoles, chlorobenzimidazoles, bromobenzimidazoles, mercaptothiazoles, mercaptobenzothiazoles, mercaptobenzimidazoles, mercaptothiadiazoles, aminotriazoles, benzotriazoles (preferably 5-methyl-benzotriazole), nitrobenzotriazoles, mercaptotetrazoles, in particular 1-phenyl-5-mercaptotetrazole, mercaptopyrimidines, mercaptotriazines, benzothiazoline-2-thione, oxazoline-thione, triazaindenes, tetrazaindenes and pentazaindenes, especially those described by Birr in Z.
  • benzothiazolium salts such as benzothiazolium salts, nitroimidazoles, nitrobenzimidazoles, chloro
  • gelatin is added in a later stage of the emulsion preparation, e.g. after washing, in order to establish optimal coating conditions and/or to establish the required thickness of the coated emulsion layer.
  • a gelatin to silver halide ratio ranging from 0.3 to 1.0 is then obtained, wherein extra gelatin added is not required to have a composition as specific as in the preparation step of the grains according to the method of the present invention.
  • Another binder may also be added instead of or in addition to gelatin or gelatin derivatives as e.g. phthalated gelatin.
  • Useful vehicles, vehicle extenders, vehicle-like addenda and vehicle related addenda have been described e.g. in Research Disclosures Nos 36544 (1994) and 38957 (1996), Chapter II.
  • the gelatin binder of the photographic material having at least one gelatinous emulsion according to the present invention can be forehardened with appropriate hardening agents such as those of the epoxide type, those of the ethylenimine type, those of the vinylsulfone type e.g. 1,3-vinylsulphonyl-2-propanol, chromium salts as e.g. chromium acetate and chromium alum, aldehydes e.g. formaldehyde, glyoxal, and glutaraldehyde, N-methylol compounds e.g.
  • dimethylol-urea and methyloldimethylhydantoin dioxan derivatives e.g. 2,3-dihydroxydioxan, active vinyl compounds e.g. 1,3,5-triacryloyl-hexahydro-s-triazine, active halogen compounds e.g. 2,4-dichloro-6-hydroxy-s-triazine, and mucohalogenic acids e.g. mucochloric acid and mucophenoxychloric acid.
  • These hardeners can be used alone or in combination.
  • the binder can also be hardened with fast-reacting hardeners such as carbamoylpyridinium salts as disclosed in US-A 4,063,952 and with the onium compounds as disclosed in EP-A 0 408 143.
  • the hydrophilic layer package of silver halide photographic materials comprising in one or more light-sensitive layers one or more (111) tabular emulsions rich in silver bromide crystals prepared according to the method of the present invention, has a swelling degree of not more than 200 %.
  • Said swelling degree is determined by means of the following procedure: a sample of the coated material is incubated at 57 °C and 34% RH for 3 days, whereafter the thickness (a) of the layer assemblage is measured. Thereafter the sample is immersed in distilled water at 21°C for 3 minutes and the thickness (b) of the swollen layer is measured. The swelling ratio is then calculated as: (b-a)/a x 100 (%) .
  • gelatinous emulsions comprising tabular grains rich in silver bromide of the present invention can be used in various types of photographic elements, e.g. black and white silver halide photographic materials, like materials used for X-ray diagnostic purposes, or colour sensitive materials.
  • said photographic element or material comprises a support and on one or on each side thereof one or more silver halide emulsion layer(s) coated from a gelatinous emulsion according to the present invention. More specifically said photographic material is a single-side or double-side coated X-ray material.
  • the single-side coated X-ray material may contain one single emulsion layer, as it is the case for many applications, or it can be built up by two or even more emulsion layers.
  • duplitized emulsions differing in photographic speed by at least 0.15 log E a gain in cross-over exposure in double side coated materials can be obtained.
  • the material contains blue, green and red sensitive layers each of which can be single coated, but merely consists of double or even triple layers.
  • the photographic material may contain several light-insensitive layers, e.g. a protective layer, one or more backing layers, one or more subbing layers, one or more intermediate layers e.g. filter layers and even an afterlayer containing e.g. the hardening agent(s), the antistatic agent(s), filter dyes for safety-light purposes, etc..
  • the photographic element of the present invention may further comprise various kinds of coating physical property modifying addenda as described in RD's Nos 36544 (1994) and 38957 (1996), Chapter IX, wherein coating aids, plasticizers and lubricants, antistats and matting agents have been described.
  • Development acceleration can be accomplished by incorporating in the emulsion layer or adjacent layers various compounds, preferably polyalkylene derivatives having a molecular weight of at least 400 such as those described in e.g. US-A's 3,038,805; 4,038,075 and 4,292,400 as well as in EP-A's 0 634 688 and 0 674 215.
  • the photographic element of the present invention may further comprise various other additives such as e.g. compounds improving the dimensional stability of the photographic element, UV-absorbers, spacing agents and plasticizers.
  • UV-absorbers are e.g. aryl-substituted benzotriazole compounds as described in US-A 3,533,794, 4-thiazolidone compounds as described in US-A 3,314,794 and 3,352,681, benzophenone compounds as described in JP-A 2784/71, cinnamic ester compounds as described in US-A's 3,705,805 and 3,707,375, butadiene compounds as described in US-A 4,045,229, and benzoxazole compounds as described in US-A 3,700,455 and those described in RD's Nos. 36544 (1994) and 38957 (1996), Chapter VI, wherein also suitable optical brighteners are mentioned. UV-absorbers are especially useful in colour materials where they prevent the fading by light of the colour images formed after processing.
  • Spacing agents can be present of which, in general, the average particle size is comprised between 0.2 and 10 ⁇ m Spacing agents can be soluble or insoluble in alkali. Alkali-insoluble spacing agents usually remain permanently in the photographic element, whereas alkalisoluble spacing agents usually are removed therefrom in an alkaline processing bath. Suitable spacing agents can be made e.g. of polymethyl methacrylate, of copolymers of acrylic acid and methyl methacrylate, and of hydroxypropylmethyl cellulose hexahydrophthalate. Other suitable spacing agents have been described in US-A 4,614,708.
  • Suitable additives for improving the dimensional stability of the photographic element are e.g. dispersions of a water-soluble or hardly soluble synthetic polymer e.g. polymers of alkyl(meth)acrylates, alkoxy(meth)acrylates, glycidyl (meth)acrylates, (meth)acrylamides, vinyl esters, acrylonitriles, olefins, and styrenes, or copolymers of the above with acrylic acids, methacrylic acids, ⁇ , ⁇ -unsaturated dicarboxylic acids, hydroxyalkyl (meth)acrylates, sulphoalkyl (meth)acrylates, and styrene sulphonic acids.
  • a water-soluble or hardly soluble synthetic polymer e.g. polymers of alkyl(meth)acrylates, alkoxy(meth)acrylates, glycidyl (meth)acrylates, (meth)acrylamides, vinyl esters,
  • the photographic material may contain several non-light sensitive layers, e.g. an antistress topcoat layer, one or more backing layers, and one or more intermediate layers eventually containing filter dyes or antihalation dyes that absorb scattering light and thus promote the image sharpness.
  • Suitable light-absorbing dyes used in these intermediate layers are described in e.g. US-A's 4,092,168 and 4,311,787, in DE-A 2,453,217, and in GB-A 7,907,440. Situated in such an intermediate layer between the emulsion layers and the support there will be only a small negligable loss in sensitivity but in rapid processing conditions decolouration of the filter dye layers may form a problem.
  • One or more backing layers can be provided at the non-light sensitive side of the support of materials coated with at least one emulsion layer at only one side of the support.
  • These layers which can serve as anti-curl layer can contain e.g. matting agents like silica particles, lubricants, antistatic agents, light absorbing dyes, opacifying agents, e.g. titanium oxide and the usual ingredients like hardeners and wetting agents.
  • the support of the photographic material may be opaque or transparent, e.g. a paper support or resin support.
  • a paper support preference is given to one coated at one or both sides with an ⁇ -olefin polymer, e.g. a polyethylene layer which optionally contains an anti-halation dye or pigment.
  • an organic resin support e.g. cellulose nitrate film, cellulose acetate film, poly(vinyl acetal) film, polystyrene film, poly(ethylene terephthalate) or poly(ethylene naphthalate) film, polycarbonate film, polyvinylchloride film or poly- ⁇ -olefin films such as polyethylene or polypropylene film.
  • the thickness of such organic resin film is preferably comprised between 0.07 and 0.35 mm.
  • These organic resin supports are preferably coated with a subbing layer which can contain water insoluble particles such as silica or titanium dioxide.
  • the photographic material containing tabular grains prepared according to the present invention can be image-wise exposed by any convenient radiation source in accordance with its specific application.
  • processing conditions and composition of processing solutions are dependent from the specific type of photographic material in which the tabular grains prepared according to the present invention are applied.
  • materials for X-ray diagnostic purposes said materials may be adapted to rapid processing conditions.
  • an automatically operating processing apparatus is used provided with a system for automatic regeneration (replenishment) of the processing solutions.
  • the forehardened material may be processed using one-part package chemistry or three-part package chemistry, depending on the processing application determining the degree of hardening required in said processing cycle. Applications within total processing times of 30 seconds and lower up to 90 seconds, known as common praxis, are possible. From an ecological point of view it is e.g. possible to use sodium thiosulphate instead of ammonium thiosulphate.
  • Emulsions Nos. 1-4 were prepared according to the Examples described in EP-A 0 577 886.
  • a nucleation step was performed by introducing solution A and solution B simultaneously in dispersion medium C both at a flow rate of 25 ml/min during 28 seconds. After a physical ripening time of 15 minutes during which the temperature was risen to 70 °C, 13.02 g of phtalated gelatin, dissolved in 250 ml of water, was added and the mixture was stirred for an additional 5 minutes. Then a first growth step was performed by introducing simultaneously during 564 seconds solution (A) at a flow rate of 5 ml/min and solution B in such a way that a constant silver potential of -33 mV is maintained.
  • a second growth step was performed by introducing by a double jet during 3763 seconds solution A starting at a flow rate of 5 ml/min and linearly increasing the flow rate to an end value of 25 ml/min, and solution B at an increasing flow rate in order to maintain a constant silver potential value of -33 mV.
  • the precipitation scheme was identical to emulsion No. 1 with the exception that during the two growth steps the silver potential was maintained at -3 mV instead of -33 mV.
  • the end volume was likewise about 1 l.
  • a nucleation step was performed by introducing solution A and solution B simultaneously in dispersion medium C both at a flow rate of 25 ml/min during 28 seconds. After a physical ripening time of 15 minutes during which the temperature was risen to 70 °C, 13.02 g of phtalated gelatin, dissolved in 250 ml of water, was added and the mixture was stirred for an additional 5 minutes. Then a first growth step was performed by introducing simultaneously during 425 seconds solution A starting at a flow rate of 5 ml/min and linearly increasing the flow rate to an end value of 25 ml/min, and solution B at an increasing flow rate as to maintain a constant silver potential value of -33 mV.
  • a second growth step was performed by introducing simultaneously during 440 seconds solution A starting at a flow rate of 25 ml/min and linearly increasing the flow rate to an end value of 56 ml/min, and solution B at an increasing flow rate in order to maintain a constant silver potential value of -33 mV.
  • a third growth step was performed by introducing simultaneously during 445 seconds solution A starting at a flow rate of 56 ml/min and linearly increasing the flow rate to an end value of 100 ml/min, and solution B at an increasing flow rate as to maintain a constant silver potential value of -33 mV.
  • the precipitation scheme was identical to that of emulsion No.3 with the exception that during the three growth steps the silver potential was maintained at -3 mV instead of -33 mV.
  • the end volume was likewise about 1 liter.
  • a nucleation step was performed by introducing solution A and solution B simultaneously in dispersion medium C both at a flow rate of 16 ml/min during 46 seconds. After a physical ripening time of 29 minutes during which the temperature was risen to 70 °C, pH was adjusted to a value of 5.8 and 3 minutes later solution G was added and the mixture was stirred for an additional 6 minutes.
  • a neutralization step was introduced by adding solution (B1) at an addition rate of 3.75 ml/min. during 80 seconds, followed by a first growth step by introducing simultaneously during 200 seconds solution (A) at a flow rate of 3.75 ml/min and solution (B1) in such a way that a constant pAg value of 8.58 (silver potential of 18 mV vs. a silver/silver chloride reference electrode) was maintained.
  • a second growth step was performed by introducing by a double jet during 2588 seconds solution A starting at a flow rate of 3.75 ml/min and linearly increasing the flow rate to an end value of 15 ml/min, and solution (B1) at an increasing flow rate in order to maintain a constant pAg of 8.58 (silver potential of 18 mV).
  • a second growth step was performed by introducing by a double jet during 2391 seconds solution A starting at a flow rate of 15 ml/min and linearly increasing the flow rate to an end value of 25 ml/min, and solution (B1) at an increasing flow rate in order to maintain a constant pAg of 8.58 (silver potential of 18 mV).
  • the circulation rate of the vessel mixture through the ultrafiltration module was 2 liter/min.
  • the dead volume was 250 ml. In this way a precipitation efficiency of 360 g AgNO 3 /liter is achieved.
  • the precipitation scheme was identical to that of emulsion 1 except for the presence in of solution (G) of 42.5 g instead of 20 g of phthalated gelatine.
  • the precipitation scheme was identical to that of emulsion 1 except for the presence in solution (G) of 20 g of an inert low viscous gelatin instead of 20 g of phthalated gelatine.
  • the precipitation scheme was identical to that of emulsion 1 except for the presence in solution (G) of 42.5 g of an inert low viscous gelatine instead of 20 g of phthalated gelatine.
  • the emulsions prepared according to the present invention are containing a ratio by number of of hexagonal tabular grains to triangular tabular crystals of more than 10:1 and even of more than 20:1, opposite to the comparative emulsions as disclosed in EP-A 0 577 886. It can thus be concluded that the ⁇ 111 ⁇ tabular grains rich in silver bromide prepared according to the method of the present invention are substantially hexagonal grains.
  • the emulsions were further redispersed and chemically ripened to an optimal fog-sensitivity relationship after addition of compounds providing sulfur and gold as chemical sensitizers.
  • Anhydro-5,5'-dichloro-3,3'-bis-(n.sulfobutyl)-9-ethyloxacarbocyanine hydroxide was added as a green sensitizer.
  • Each emulsion was stabilized with 4-hydroxy-6-methyl-1,3,3a,7-tetra-azaindene and after addition of the normal coating additives the solutions were coated simultaneously together with a protective layer containing 1.1 g of gelatin per m 2 and per side on both sides of a polyethylene terephthalate film support having a thickness of 175 ⁇ m.
  • the resulting photographic material was containing per side of the support an amount of silver halide corresponding to 3.90 grams of AgNO 3 per m 2 .
  • Fixation was carried out in fixer G334, also marketed by Agfa-Gevaert N.V..
  • Table 2 hereinafter summarizes as sensitometric characteristics for the comparative material (MC-1) and for the inventive materials (MI-1 to MI-4) the fog F, sensitivity (speed) S and contrast (gradation) C of the samples after processing and the covering power (CP) calculated from the ratio of maximum density and grams of coated silver before processing.
  • a nucleation step was performed by introducing solution A and solution B1 simultaneously in dispersion medium C both at a flow rate of 16 ml/min during 46 seconds. After a physical ripening time of 25 minutes during which the temperature was risen to 70 °C, 42.5 g of gelatin having a methionine content of 13 ⁇ mole/mole of gelatin, dissolved in 460 ml of water, was added and the mixture was stirred for an additional 6 minutes. After a neutralization step by addition of solution B1 at a rate of 3.75 ml/min.
  • a first growth step was performed by introducing simultaneously during 200 seconds solution (A) at a flow rate of 3.75 ml/min and solution B in such a way that a constant pAg of 8.58 (silver potential of 18 mV) is maintained. Then growth was further performed by introducing by a double jet during 2588 seconds solution A starting at a flow rate of 3.75 ml/min and linearly increasing the flow rate to an end value of 15 ml/min. Solution B1 was added at an increasing flow rate in order to maintain a constant pAg value of 8.58.
  • a second growth step was performed after a physical ripening time of 5 minutes by introducing by a double jet during 2391 seconds solution A starting at a flow rate of 15 ml/min and linearly increasing the flow rate co an end value of 25 ml/min.
  • Solution B1 was added at an increasing flow rate in order to maintain the same constant pAg value of 8.58.
  • An average methionine content of 13 ⁇ mole/mole of gelatin was measured.
  • Emulsion No. d Vol. ( ⁇ m) d Tab. ( ⁇ m) s dTab. t Tab ( ⁇ m) %T hex. %T triang T hex /T triang Comp.-5 0.51 0.91 0.30 0.21 96 4 24.0 Inv.-5 0.50 0.90 0.22 0.20 97 3 24.0
  • inventive emulsion No. 5 not only shows the same degree of morphologic homogeneity with respect to inventive emulsion No. 5, but moreover shows a significantly higher degree of homogeneity on the diameter (s dTab. defined hereinbefore as standard deviation on average crystal diameter).
  • This effect is specifically related with the methionine content of the gelatin added after nucleation.
  • a nucleation step was performed by introducing solution A and solution B1 simultaneously in dispersion medium C both at a flow rate of 16 ml/min during 46 seconds. After a physical ripening time of 2 minutes the temperature was risen to 70 °C in a time interval of 25 minutes. 2 minutes later the pH value was adjusted to a value of 5.8. 4 g of gelatin having a methionine content of 50 ⁇ mole/mole of gelatin, dissolved in 460 ml of water, was added and the mixture was stirred for an additional 6 minutes.
  • a first growth step was performed by introducing simultaneously during 180 seconds solution (A) at a flow rate of 5.2 ml/min and solution B in such a way that a constant pAg of 8.58 (silver potential of 18 mV) was maintained. Then growth was further performed by introducing by a double jet during 3189 seconds solution A starting at a flow rate of 5.2 ml/min and linearly increasing the flow rate to an end value of 9.9 ml/min. Solution B1 was added at an increasing flow rate in order to maintain a constant pAg value of 8.58.
  • a second growth step was performed after a physical ripening time of 5 minutes by introducing by a double jet during 2391 seconds solution A starting at a flow rate of 9.9 ml/min and linearly increasing the flow rate to an end value of 15.4 ml/min.
  • Solution B1 was added at an increasing flow rate in order to maintain the same constant pAg value of 8.58.
  • An average methionine content of 22 ⁇ mole/mole of gelatin was measured.
  • the corpual amount of gelatin in the nucleation step was 71 %.
  • As no ultrafiltration step was performed during precipitation the maximum amount of silver halide, expressed as an equivalent amount of silver nitrate, was 83 g/l at the end of the precipitation.
  • a dispersion medium (C) consisting of 900 ml of demineralized water , 10 g of oxidized gelatin having a methionine content of 11 mole per mole of gelatin and 4.26 ml of a 6 molar solution of sulfuric acid; the temperature was established at 51 °C and a pAg value of 8.77 was measured, corresponding with an electrochemical potential of 18 mV, measured with a silver electrode versus a silver/silver chloride reference electrode.
  • This comparative emulsion No. 7 was further prepared in the same way as emulsion No. 6, except for the differences in amounts of demineralized water in the starting vessel as indicated above.
  • the same preparation procedure was followed as for the comparative emulsion No. 6, except for the composition of the dispersion medium (C), which was prepared with 900 ml of demineralized water , 2.5 g of oxidized gelatin having a methionine content of 11 mole per mole of gelatin and 4.26 ml of a 6 molar solution of sulfuric acid; the temperature was established at 51 °C and a pAg value of 8.77 was measured, corresponding with an electrochemical potential of 18 mV, measured with a silver electrode versus a silver/silver chloride reference electrode.
  • C dispersion medium

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Claims (10)

  1. Procédé pour la préparation d'une émulsion contenant des grains riches en bromure d'argent en présence de gélatine faisant office de colloide protecteur dans un réacteur, selon lequel on obtient un rendement supérieur à 250 g d'halogénure d'argent précipité exprimé comme nitrate d'argent par litre de mélange dans le réacteur,
    au moins 70 % d'une surface de projection totale de tous les grains étant constitués par des grains tabulaires {111} possédant un indice de forme moyen supérieur à 2:1 et une épaisseur moyenne de 0,05 à 0,30 µm et un rapport numérique entre grains tabulaires hexagonaux et cristaux tabulaires triangulaires contenus étant supérieur à 10:1, ledit procédé comportant les étapes suivantes :
    préparation dans un réacteur d'un milieu dispersant gélatineux contenant une quantité initiale de gélatine correspondant à moins de 50 % d'une quantité totale de gélatine utilisée selon ledit procédé, ladite quantité initiale de gélatine possédant une teneur moyenne en méthionine inférieure à 30 µmoles par mole et ledit milieu dispersant possédant un volume inférieur à 2 litres par 500 g d'halogénure d'argent exprimé comme nitrate d'argent à précipiter;
    précipitation de germes d'halogénure d'argent y-dedans par la précipitation à double jet d'une solution aqueuse de nitrate d'argent et d'une solution aqueuse contenant des ions halogénures, pendant laquelle moins de 10 % en poids d'une quantité totale de nitrate d'argent utilisé sont consommés;
    addition de gélatine dans ledit réacteur dans une quantité supérieure à 50 % d'une quantité totale de gélatine utilisée selon ledit procédé;
    croissance desdits germes d'halogénure d'argent par précipitation complémentaire d'halogénure d'argent par la précipitation à double jet d'une solution aqueuse de nitrate d'argent et d'une solution aqueuse contenant des ions halogénures, pendant laquelle plus de 90 % en poids d'une quantité totale de nitrate d'argent sont consommés,
    concentration du volume dudit mélange réactionnel obtenu au courant des étapes de précipitation et de croissance dans ledit réacteur par ultrafiltration.
  2. Procédé selon la revendication 1, caractérisé en ce que lesdits grains tabulaires {111} riches en bromure d'argent sont constitués de bromure d'argent, de bromoiodure d'argent, de bromochlorure d'argent ou de bromochloroiodure d'argent.
  3. Procédé selon la revendication 2, caractérisé en ce que de l'iodure d'argent est contenu dans ledit bromoiodure d'argent ou bromochloroiodure d'argent dans une quantité maximale de 3 % de moles.
  4. Procédé selon la revendication 2 ou 3, caractérisé en ce que de l'iodure provient d'un agent libérant de l'iodure.
  5. Procédé selon l'une quelconque des revendications 1 à 4, caractérisé en ce qu'un épaisseur moyenne desdits grains tabulaires {111} varie entre 0,05 et 0,20 µm.
  6. Procédé selon l'une quelconque des revendications 1 à 5, caractérisé en ce que l'addition de gélatine dans le réacteur qui diffère de ladite quantité initiale de gélatine s'effectue dans une quantité supérieure à 80 % en poids de la quantité totale de gélatine utilisée, ladite gélatine qui diffère de ladite quantité initiale de gélatine contenant de la méthionine dans une quantité supérieure à 30 µmoles par gramme.
  7. Emulsion gélatineuse préparée conformément au procédé tel que défini dans l'une quelconque des revendications 1 à 6, caractérisée en ce que ladite émulsion contient des grains de bromure d'argent, de bromoiodure d'argent, de bromochlorure d'argent ou de bromochloroiodure d'argent et en ce qu'au moins 70 % de la surface de projection totale de tous les grains sont constitués par des grains tabulaires {111} possédant un indice de forme moyen supérieur à 2:1 et une épaisseur moyenne de 0,05 à 0,30 µm et en ce qu'un rapport numérique entre grains tabulaires hexagonaux et cristaux tabulaires triangulaires est supérieur à 10:1.
  8. Emulsion gélatineuse selon la revendication 7, caractérisé en ce qu'un rapport numérique entre grains tabulaires hexagonaux et cristaux tabulaires triangulaires est supérieur à 20:1.
  9. Matériau photographique comprenant un support ainsi que sur une ou sur les deux faces dudit support une ou plusieurs couches d'émulsion aux halogénures d'argent sensibles à la lumière appliquées à partir d'une émulsion gélatineuse telle que définie dans la revendication 7 ou 8.
  10. Matériau photographique selon la.revendication 9, caractérisé en ce qu'il est un matériau radiographique émulsionné sur une face ou sur les deux faces.
EP19970203313 1997-10-24 1997-10-24 Procédé pour la préparation des crystaux tabulaires (111) riches en bromure d'argent et morphologiquement homogènes Expired - Lifetime EP0911687B1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
DE69729869T DE69729869T2 (de) 1997-10-24 1997-10-24 Verfahren zur Herstellung von morphologisch homogenen silberbromidreichen tafelförmigen (111)-Kristallen
EP19970203313 EP0911687B1 (fr) 1997-10-24 1997-10-24 Procédé pour la préparation des crystaux tabulaires (111) riches en bromure d'argent et morphologiquement homogènes
US09/168,986 US6087085A (en) 1997-10-24 1998-10-09 Preparation method of morphologically homogeneous (111) tabular crystals rich in silver bromide
JP30107298A JPH11223894A (ja) 1997-10-24 1998-10-22 臭化銀に富む形態学的に均一な｛１１１｝平板状結晶の製造法

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EP19970203313 EP0911687B1 (fr) 1997-10-24 1997-10-24 Procédé pour la préparation des crystaux tabulaires (111) riches en bromure d'argent et morphologiquement homogènes

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EP0911687B1 true EP0911687B1 (fr) 2004-07-14

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US6319659B1 (en) 1998-10-13 2001-11-20 Konica Corporation Silver halide emulsion, preparation method thereof and silver halide photographic light sensitive material
EP1103847B1 (fr) * 1999-11-26 2002-09-11 Agfa-Gevaert Pellicule photographique à l'halogénure d'argent ayant un pouvoir opacifiant accru et un ton de l'image noir bleuâtre "plus froid"
US6342338B1 (en) 1999-11-26 2002-01-29 Agfa-Gevaert Silver halide photographic material exhibiting increased covering power and “colder” blue-black image tone
US6558892B2 (en) * 2000-08-01 2003-05-06 Agfa-Gevaert Method of preparing ultrathin light-sensitive tabular grain emulsions rich in silver bromide
US6737228B2 (en) * 2001-05-22 2004-05-18 Agfa-Gevaert Film material exhibiting a “colder” blue-black image tone and improved preservation characteristics

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US5587281A (en) * 1994-07-14 1996-12-24 Fuji Photo Film Co., Ltd. Method for producing silver halide grain and silver halide emulsion using the grain
US5567580A (en) * 1994-10-26 1996-10-22 Eastman Kodak Company Radiographic elements for medical diagnostic imaging exhibiting improved speed-granularity characteristics
EP0843208A1 (fr) * 1996-11-15 1998-05-20 Agfa-Gevaert N.V. Procédé pour la préparation de grains tubulaires riches en bromure d'argent en présence de gélatines spécifiques

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DE69729869D1 (de) 2004-08-19
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EP0911687A1 (fr) 1999-04-28

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