Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/0051—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
  • G03C1/035—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein characterised by the crystal form or composition, e.g. mixed grain
• • 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
  • G03C1/04—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with macromolecular additives; with layer-forming substances
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
  • G03C1/067—Additives for high contrast images, other than hydrazine compounds
• • 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
  • G03C2001/03529—Coefficient of variation
• • 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
  • G03C2001/03594—Size of the grains

Definitions

• the present invention relates to a silver halide emulsions comprising tabular triangular crystals, to the preparation method thereof and to light-sensitive silver halide photographic materials containing said emulsions.
• the anisotropic growth of the said tabular grains is 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 566 076; 506 947; 518 066 and 513 722 and US-A 4,797,354 are related with the preparation of monodisperse hexagonal tabular crystals, respectively with the preparation of tabular emulsions having a high percentage (at least 90 %) of hexagonal, tabular crystals.
• a light-sensitive silver bromide or silver bromoiodide emulsion comprising silver bromide or silver bromoiodide tabular triangular grains, said tabular triangular grains having an average grain thickness of less than 0.3 ⁇ m, an average crystal diameter of at least 0.6 ⁇ m; an average aspect ratio of at least 2:1; a variation coefficient of less than 40 %, said grains accounting for a total projective area of at least 30 %; characterised in that the thickness ratio of triangular tabular grains to hexagonal tabular grains is from 1.3 to 0.7.
• a method is further provided to prepare emulsions comprising said triangular tabular grains as disclosed hereinbefore comprising the steps of:
• This invention also provides a silver halide light-sensitive photographic material having a support and, provided thereon, at least one hydrophilic colloid layer including at least one light-sensitive emulsion comprising the tabular triangular silver bromide or silver bromoiodide grains as defined hereinbefore.
• the said shape is considered to be triangular as soon as the length of the smallest side is less than 1/10th of the lenght of the largest side.
• emulsions comprising tabular triangular silver bromide or silver bromoiodide grains as defined hereinbefore, wherein the said tabular grains have an aspect ratio of at least 2:1.
• the term "aspect ratio" can be applied as the silver bromide or silver bromoiodide tabular triangular grains of this invention are crystals having two parallel major faces with a ratio between the diameter of a circle having the same area as these faces, and the thickness, which is the distance between the said two parallel faces, being equal to at least 2:1.
• said aspect ratio is at least 5:1, and more still more preferably at least 8:1, wherein an average crystal diameter of at least 0.6 ⁇ m is preferred; a crystal thickness of less than 0.3 ⁇ m, more preferably less than 0.2 ⁇ m and a variation coefficient of less than 40 % and still more preferably less than 25 %.
• the main photographic advantages of tabular grains compared to normal globular grains are a high covering power at high forehardening levels, a high developability and a higher sharpness especially in double side coated spectrally sensitised materials.
• the light-sensitive silver halide emulsions comprising tabular grains, and particularly said tabular triangular grains according to this invention, are characterised in the preparation step by the presence of an onium compound and a protective colloid in a weight ratio (COSI) amount of from 0.03 to 0.5, more preferably in a weight ratio amount of from 0.05 to 0.30 and by a well-defined pAg value range of from 9.5 to 8.0, and more preferably from 9.5 to 8.8, in the nucleation and/or growth step.
• COSI weight ratio
• the thickness ratio of triangular tabular crystals to hexagonal tabular crystals is from 1.3 to 0.7, as will become apparent from the Examples. This means that an analogous growth mechanism for triangular as for hexagonal crystals is observed when said triangular crystals are prepared according to the method of this invention, opposite to thickness ratios obtained by application of preparation methods according to e.g. FR 2 534 036.
• gelatin or colloidal silica sol is used alone or in a combination of gelatin and colloidal silica sol in the method of this invention. It can, however, be replaced in part or integrallly by synthetic, semi-synthetic, or natural polymers.
• Synthetic substitutes for gelatin are e.g. polyvinyl alcohol, poly-N-vinyl pyrrolidone, polyvinyl imidazole, polyvinyl pyrazole, polyacrylamide, polyacrylic acid, and derivatives thereof, in particular copolymers thereof.
• Natural substitutes for gelatin are, e.g., other proteins such as zein, albumin and casein, cellulose, saccharides, starch, and alginates.
• the semi-synthetic substitutes for gelatin are modified natural products, e.g., gelatin derivatives obtained by conversion of gelatin with alkylating or acylating agents or by grafting of polymerisable monomers on gelatin, and cellulose derivatives such as hydroxyalkyl cellulose, carboxymethyl cellulose, phthaloyl cellulose, and cellulose sulphates.
• the gelatin can be lime-treated or acid-treated gelatin. The preparation of such gelatin types has been described in e.g. "The Science and Technology of Gelatin", edited by A.G. Ward and A. Courts, Academic Press 1977, page 295 and next pages.
• the gelatin can also be an enzyme-treated gelatin as described in Bull. Soc. Sci. Phot. Japan, N° 16, page 30 (1966).
• silica sols are used in the method of this invention as a sole protective colloid in the preparation of silver halide emulsions or together with gelatin as set forth hereinbefore.
• Commercially available silica sols are the "Syton” silica sols (trademarked products of Monsanto Inorganic Chemicals Div.), the “Ludex” silica sols (trademarked products of du Pont de Nemours & Co., Inc.), the "Nalco” and “Nalcoag” silica sols (trademarked products of Nalco Chemical Co), the "Snowtex” silica sols of Nissan Kagaku K.K.
• Particle sizes of the silica sol particles are in the range from 3 nm to 30 ⁇ m, but smaller particles in the range from 3 nm to 0.3 ⁇ m are preferred.
• Variation from the weight ratio amount of the protective colloid(s) versus the co-stabilising onium compound(s) during the preparation steps that are characterising the preparation method of this invention can be attained by adding the said compound(s) in two or more portions during the preparation process of the tabular triangular crystals according to this invention.
• NH 4 + - ions are thereby excluded as onium compounds as NH 4 Br may be used as a halide salt in the preparation method of emulsion grains of this invention.
• the grains having silica as a protective colloid according to this invention are preferred having an average grain thickness of not more than 0.3 ⁇ m and, more preferably, not more than 0.2 ⁇ m.
• an average aspect ratio of at least 5:1 and, more preferably, of at least 8:1 and still more preferably of at least 12:1 is preferred for the grains according to this invention.
• a total projective area of the said grains of at least 70% is highly preferred and a total projective area of at least 90% is even more preferred.
• Iodide ions can be provided by anorganic iodide salts and/or organic compounds releasing iodide ions as has e.g. been described in EP-A's 0 561 415, 0 563 701, 0 563 708, 0 649 052 and 0 651 284. Iodide ion concentrations up to 10 mole % may be present but concentrations up to 3 mole % are particularly preferred.
• the preparation of the light-sensitive tabular triangular silver bromide or silver bromoiodide emulsions according to this invention comprises the following steps:
• the nucleation step which consists preferably of an addition by means of the double-jet method of silver nitrate and halide salts at a pBr of at least 2.0.
• Additional amounts of protective colloid and onium compound(s), may be added to the reaction vessel in one or more portions or continously in a triple-jet precipitation system. Especially preferred are additions during so called Ostwald ripening stages e.g. before the flow rate of the silver and/or halide solutions is increased in a double-jet precipitation system.
• ammonium compounds like e.g. ammonium bromide
• the following compounds represented by the following general formulae can be used: A + X - wherein
• onium compounds are disclosed in US-A 3,017,270.
• suitable examples are mentioned of trialkyl sulfonium salts, polysulfonium salts, tetraalkyl quaternary ammonium salts, quaternary ammonium salts in which the quaternary nitrogen atom is a part of a ring system, cationic polyalkylene oxide salts including e.g. quaternary ammonium and phosphonium and bis-quaternary salts.
• the said onium compounds act as effective crystal habit modifiers for the silver bromide and silver bromoiodide tabular triangular crystals.
• the action of onium compounds as a crystal habit modifier is more pronounced in the presence of colloidal silica sol, although their influence in the presence of gelatin cannot be neglected.
• the photographic emulsions comprising silver bromide and silver bromoiodide tabular triangular crystals may have a homogenous or a heterogeneous halide distribution within the crystal volume.
• a heterogenous halide distribution may be obtained by application of growth steps having a different halide composition or by conversion steps e.g. by addition of iodide ions that provide less soluble silver salts, onto existing tabular silver bromide cores or silver bromoiodide cores poor in iodide.
• a heterogeneous distribution of bromide and iodide ions a multilayered grain structure is obtained.
• the tabular triangular form has to be maintained in this case in order to get tabular triangular emulsion crystals in accordance with this invention.
• the crystals may further be doped with whatever a dope as e.g. with Rh 3+ , Ir 4+ , Cd 2+ , Zn 2+ , Ru 2+ and Pb 2+ .
• grain growth restrainers or accelerators may be added to obtain crystals with a preferred average crystal size diameter between 0.05 and 5 ⁇ m.
• grain growth accelerators are compounds carrying e.g. a thioether function.
• Silver halide nuclei can also be formed in a separate vessel and added to the reaction vessel wherein the growth step is performed. In said reaction vessel additional amounts of protective colloid and onium compound(s) may be present.
• spectral sensitisers may be added at any stage of the emulsion preparation. More preferably the said spectral sensitisers are added before chemical sensitisation.
• the light-sensitive emulsion comprising silver bromide or bromoiodide tabular triangular crystals, prepared in accordance with the present invention is, after redispersion, a so-called primitive emulsion.
• Chemical sensitisation can be performed as described in i.a. "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 sensitisation can be carried out by effecting the ripening in the presence of small amounts of compounds containing sulphur, selenium and/or tellurium e.g. thiosulphate, thiocyanate, the corresponding selenium and/or tellurium compounds, thioureas, sulphites, mercapto compounds, and rhodanines.
• the emulsions can be sensitised also by means of gold-sulphur, gold-selenium and/or gold-tellurium ripeners or by means of reductors e.g.
• tin compounds as described in GB-A 789,823, amines, hydrazine derivatives, formamidine-sulphinic acids, and silane compounds.
• Chemical sensitisation can also be performed with small amounts of Ir, Rh, Ru, Pb, Cd, Hg, Tl, Pd, Pt, or Au.
• One of these chemical sensitisation methods or a combination thereof can be used.
• a mixture can also be made of two or more separately precipitated emulsions being chemically sensitised before mixing them.
• spectral sensitisation In classical emulsion preparation spectral sensitisation traditionally follows the completion of chemical sensitisation. However, in connection with tabular grains, it is specifically considered that spectral sensitisation occurs simultaneously with or even precedes completely the chemical sensitisation step: the chemical sensitisation after spectral sensitisation is believed to occur at one or more ordered discrete sites of tabular grains.
• emulsions of the present invention may also be done with the emulsions of the present invention, wherein the chemical sensitisation 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 stabiliser(s) or antifoggant(s), one or more spectal sensitiser(s) or combinations of said ingredients.
• the light-sensitive emulsion comprising silver halide tabular triangular crystals, prepared in accordance with the present invention, may be spectrally sensitised with methine dyes such as those described by F.M. Hamer in "The Cyanine Dyes and Related Compounds", 1964, John Wiley & Sons.
• Dyes that can be used for the purpose of spectral sensitisation 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.
• a survey of useful chemical classes of spectral sensitising dyes and specific useful examples in connection with tabular grains is given in the already cited Research Disclosure Item 22534.
• An example of a useful spectral sensitiser is anhydro-5,5'-di-chloro-3,3'-bis(n-sulphobutyl)-9-ethyloxacarbo-cyanine hydroxide or anhydro-5,5'-dichloro-3,3'-bis(n-sulphopropyl)-9-ethyloxacarbo-cyanine hydroxide.
• a suitable mixture of spectral sensitisers that can be applied is anhydro-5,5'-dichloro-3,3'-bis(n-sulphobutyl)-9-ethyl oxacarbocyanine hydroxide or anhydro-5,5'-dichloro-3,3'-bis(n-sulphopropyl)-9-ethyloxacarbo-cyanine hydroxide and anhydro-5,5'-dicyano- 1,1'-diethyl-3,3'-di(2-acetoxyethyl)ethyl-imidacarbocyanine bromide. Further structures are given in EP-A 0 677 773, which is incorporated herein by reference.
• Suitable supersensitisers are, i.a., heterocyclic mercapto compounds containing at least one electronegative substituent as described e.g. in US-A 3,457,078, nitrogen-containing heterocyclic ring-substituted aminostilbene compounds as described e.g. in US-A 2,933,390 and US-A 3,635,721, aromatic organic acid-formaldehyde condensation products as described e.g. in US-A 3,743,510, cadmium salts, and azaindene compounds.
• the ratio by weight of protective colloid to silver halide is determined at the stage of precipitation and/or by further addition of protective colloid at the redispersion stage or later.
• emulsion(s) comprising silver halide tabular triangular grains prepared in accordance with the present invention may be added compounds preventing the formation of fog or stabilising the photographic characteristics prior to, during, or after the chemical ripening thereof or during the production or storage of photographic elements or during the photographic treatment thereof. Mixtures of two or more of these compounds can be used.
• Suitable examples are i.a. the 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-mercapto-tetrazole, mercaptopyrimidines, mercaptotriazines, benzothiazoline-2-thione, oxazoline-thione, triazaindenes, tetrazaindenes and pentazaindenes, especially those described
• the silver halide emulsions prepared in accordance with the present invention can be used to form one or more silver halide emulsion layers coated on a support to form a photographic silver halide element according to well known techniques.
• Two or more types of emulsions comprising silver halide tabular triangular grains that have been prepared differently according to this invention can be mixed in at least one emulsion layer for forming a photographic emulsion for use in accordance with the present invention.
• the photographic element of the present invention may comprise various kinds of surface-active agents in the photographic emulsion layer or in at least one other hydrophilic colloid layer.
• Suitable surface-active agents include non-ionic agents such as saponins, alkylene oxides e.g.
• polyethylene glycol polyethylene glycol/polypropylene glycol condensation products, polyethylene glycol alkyl ethers or polyethylene glycol alkylaryl ethers, polyethylene glycol esters, polyethylene glycol sorbitan esters, polyalkylene glycol alkylamines or alkylamides, silicone-polyethylene oxide adducts, glycidol derivatives, fatty acid esters of polyhydric alcohols and alkyl esters of saccharides; anionic agents comprising an acid group such as a carboxy, sulpho, phospho, sulphuric or phosphoric ester group; ampholytic agents such as aminoacids, aminoalkyl sulphonic acids, aminoalkyl sulphates or phosphates, alkyl betaines, and amine-N-oxides; and cationic agents such as alkylamine salts, aliphatic, aromatic, or heterocyclic quaternary ammonium salts, aliphatic or heterocyclic ring
• Such surface-active agents can be used for various purposes e.g. as coating aids, as compounds preventing electric charges, as compounds improving slidability, as compounds facilitating dispersive emulsification, as compounds preventing or reducing adhesion, and as compounds improving the photographic characteristics e.g higher contrast, sensitisation, and development acceleration.
• Development acceleration can be accomplished with the aid of 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 and in EP-A 0 634 688 and EP-A 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. hardeners and plasticisers as described below.
• additives such as e.g. compounds improving the dimensional stability of the photographic element, UV-absorbers, spacing agents. hardeners and plasticisers as described below.
• a light-sensitive photographic material coated from emulsions comprising silver halide tabular crystals having silica as a protective colloid, having a support and, thereon, at least one hydrophilic colloid layer including at least one light-sensitive silver halide emulsion layer characterised in that said light-sensitive layer comprises at least one of said emulsions.
• the layers of the photographic element can be hardened 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, bis-(vinyl sulphonyl)-methane, chromium salts e.g. chromium acetate and chromium alum, aldehydes e.g. formaldehyde, glyoxal, and glutaraldehyde, N-methylol compounds e.g.
• 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, bis-(vinyl sulphonyl)-methane, chromium salts e.g. chromium
• dimethylolurea and methyloldimethylhydantoin dioxan derivatives e.g. 2,3-dihydroxy-dioxan, 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 binders can also be hardened with fast-reacting hardeners such as carbamoylpyridinium salts as disclosed in US-P 4,063,952 and with the onium compounds as disclosed in EP-A 0 408 143.
• the emulsion may be coated on any suitable substrate such as, preferably, a thermoplastic resin e.g. polyethyleneterephthalate, polyethylene naphthalate or a polyethylene coated paper support.
• a thermoplastic resin e.g. polyethyleneterephthalate, polyethylene naphthalate or a polyethylene coated paper support.
• Suitable additives for improving the dimensional stability of the photographic element may be added i.a. 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 soluble synthetic polymer e.g. polymers of alkyl (meth)acrylates, alkoxy(meth)acrylates, glycidyl (meth)acrylates, (meth)acrylamides, vinyl esters, acryl
• Plasticisers suitable for incorporation in the emulsions according to the present invention are e.g. glycol, glycerine, or the latexes of neutral film forming polymers including polyvinylacetate, acrylates and methacrylates of lower alkanols e.g. polyethylacrylate and polybutylmethacrylate.
• Suitable UV-absorbers are i.a. 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 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.
• the average particle size of spacing agents is comprised between 0.2 ⁇ m and 10 ⁇ m.
• Spacing agents can be soluble or insoluble in alkali. Alkali-insoluble spacing agents usually remain permanently in the photographic element, whereas alkali-soluble spacing agents usually are removed therefrom in an alkaline processing bath.
• Suitable spacing agents can be made i.a. 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.
• Emulsion layers comprising silver halide tabular triangular emulsions prepared in accordance with the present invention, and more particularly thin emulsion layers, are showing remarkable improvements concerning both speed and rapid processability compared to conventional emulsions.
• the photographic silver halide tabular triangular emulsions can be used in various types of photographic elements such as i.a. in photographic elements for so-called amateur and professional photography, for graphic arts, diffusion transfer reversal photographic elements, low-speed and high-speed photographic elements, X-ray materials, micrografic materials etc..
• the photographic silver halide emulsions are used in X-ray materials.
• a material with a single or a duplitized emulsion layer coated on one or both sides of the support may contain silver halide tabular triangular emulsions according to this invention.
• the photographic material may contain several non-light sensitive layers e.g. a protective antistress topcoat layer, one or more backing layers, and one or more intermediate layers eventually containing filter- 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; DE 2,453,217 and GB-Patent 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.
• the material contains blue, green and red sensitive layers each of which can be single coated, but generally consist of double or even triple layers.
• the photographic material may contain several light-insensitive layers e.g. a protective antistress 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.
• 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 Alpha-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, triacetate film, poly(vinyl acetal) film, polystyrene film, poly(ethylene terephthalate) film, polycarbonate film, polyvinylchloride film or poly-Alpha-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, including the steps of developing, fixing, rinsing and drying.
• an automatically operating processing apparatus is used provided with a system for automatic regeneration 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 up to 30 seconds are possible, whereas applications up to 90 seconds are known as common praxis. From an ecological point of view it is even possible to use sodium thiosulphate instead of ammonium thiosulphate and to reduce the regeneration amounts of developer and fixer.
• Solution 1 1.5 liter of an aqueous solution containing 500 grams of silver nitrate.
• Solution 2 0.525 liter of an aqueous solution containing 126 grams of potassium bromide.
• Solution 3 0.975 liter of an aqueous solution containing 230.4 grams of potassium bromide and 0.5 grams of potassium iodide.
• Emulsion 1 (comparative):
• the stirring rate was 150 rpm in the vessel and a UAg-value of -53 mV vs. a silver/silver chloride reference electrode was measured at 70°C.
• 2160 ml of demineralised water were present wherein 1.3 g of KBr and 12.5 g of inert bone gelatin were put.
• a double jet precipitation was started after 10 minutes using solutions 1 and 2 which continued for 2 minutes 42 seconds. During this precipitation, a mV value of -30 mV was measured. The flowing rate of both solutions was equal to 7.5 ml per minute. After the said time, the flowing rate was increased linearly from 7.5 to 22.2 ml/min during 31 minutes and 36 seconds. During this time interval the same constant mV value was measured. 5 minutes later a neutralisation phase was started.
• solution 1 was run at a rate of 7.5 ml/min and a value of + 70 mV was measured, whereafter the second growth step was started.
• solution 1 was injected in the reaction vessel at a linearly increasing rate, going from 7.5 ml per minute to 37.5 ml per minute at the end of the precipitation.
• the mV value was kept constant at + 70 mV for the whole time while injecting solution 3 together with solution 1.
• Emulsion 2 (comparative):
• Emulsion 3 (invention):
• the initial UAg measured vs. a silver/silver chloride reference electrode was adjusted at -34 mV before starting the precipitation.
• a nucleation step was performed by introducing solution A and solution B1 simultaneously in dispersion medium C both at a flow rate of 10 ml/min during 30 seconds. After a physical ripening time of 20 min the pH value was adjusted to a value of 3.0 and the solution was stirred for another 5 minutes. Then a growth step was performed by introducing by a double jet during 66 minutes solution A starting at a flow rate of 2.5 ml/min and linearly increasing the flow rate to an end value of 12.5 ml/min, and solution B1 at an increasing flow rate in order to maintain a constant mV-value -12 mV. During that time the phosphonium compound was poured into the reaction vessel in three steps during grain growth (after 26 minutes 35 seconds, 42 minutes 43 seconds and 55 minutes 19 seconds respectively) and an amount of 8 ml was added during each step.
• Emulsion 4 (invention) :
• the initial UAg measured vs. a silver/silver chloride reference electrode was adjusted at -34 mV before starting the precipitation.
• a nucleation step was performed by introducing solution A and solution B1 simultaneously in dispersion medium C both at a flow rate of 10 ml/min during 30 seconds. After a physical ripening time of 20 min 3.25 ml of a 10 % solution of 3-carboxymethylthio-1-2-4-triazole and 20 ml of a 10 % solution of imidazol were added and the pH value was adjusted to a value of 3.0. The solution was stirred for another 5 minutes.
• a growth step was performed by introducing by a double jet during 66 minutes solution A starting at a flow rate of 2.5 ml/min and linearly increasing the flow rate to an end value of 12.5 ml/min, and solution B1 at an increasing flow rate in order to maintain a constant UAg-value of + 5 mV.
• Emulsion 5 (invention):
• a nucleation step was performed by introducing solution A and solution B1 simultaneously in dispersion medium C both at a flow rate of 10 ml/min during 30 seconds. After a physical ripening time of 20 min 120 ml of a silica sol solution of "Kieselsol 500" (15 %) and 80 ml of the same co-stabilising phosphonium compound were added, together with 250 ml of demineralised water, and the pH value was adjusted to a value of 3.0. The solution was stirred for another 5 minutes.
• a growth step was performed by introducing by a double jet during 2 minutes and 38 seconds a solution A starting at a flow rate of 2.5 ml/min, whereafter a linearly increasing flow rate to an end value of 7.5 ml/min was applied during 32 minutes and 30 seconds.
• Solution B1 was added together with solution A at increasing flow rate in order to maintain a constant UAg-value of + 8 mV.
• the average diameter d EM , average thickness "t", average aspect ratio AR were obtained from electron microscopic photographs: the diameter of the grain was defined as the diameter of the circle having an area equal to the projected area of the grain as viewed in the said photographs.
• Tables 1 and 2 A separate analysis of the triangularly-shaped and the hexagonally-shaped crystals is given in Tables 1 and 2 and a comparison between ratios of both differently shaped crystals is given in Table 3.
• Table 1 Evaluation of triangularly-shaped crystals in the Emulsions.
• Emulsion d M ( ⁇ m) d EM ⁇ t ( ⁇ m) AR 1 (comp) 0.54 0.45 0.31 0.26 1.8 2 (comp) 0.70 0.64 0.33 0.36 2.2 3 (inv) 0.53 1.76 0.19 0.10 18 4 (inv) 0.56 1.43 0.29 0.08 18 5 (inv) 0.55 1.56 0.36 0.11 14 Table 2. Evaluation of hexagonally-shaped crystals in the Emulsions.
• the ratio of AR-values for triangular and hexagonal crystals leads to values comprised between 1.3 and 0.9 for crystals prepared according to the method of this invention. This is an indication for a comparable thickness of triangular and hexagonal crystals present in an emulsion prepared by the method of this invention. Opposite thereto for the comparative emulsions the triangularly-shaped crystals are clearly thicker than the hexagonally-shaped ones: an average ratio of 2 makes the ratio of aspect ratios in this case be 0.4-0.6.
• the total number of the triangles is remarkably higher for the emulsions prepared according to the method of this invention (25-55 % vs. 10-15 % for the comparative emulsions).
• the difference in projected surface area of the triangular crystals for the emulsions according to this invention is 25-70 % vs. only 4-5 % for the comparative emulsions.
• the emulsions were chemically ripened with sulphur and gold at 47°C for 4 hours in order to get an optimised relation between fog and sensitivity and were stabilised with 4-hydroxy-6-methyl-1,3.3a-tetrazaindene before coating on one side of a polyester support of 175 ⁇ m thickness.
• toluene thiosulphonic acid was used as a weakly oxidising predigestion agent before starting the chemical ripening, followed by the addition of 362.5 mg of anhydro-5,5'-dichloro-3,3'-bis(n.sulfobutyl)-9-ethyloxacarbo-cyanine hydroxide as spectral sensitiser, per mole of silver bromoiodide. Further an amount of 200 mg of 1-p-carboxy-phenyl-5-mercaptotetrazole was added.
• the emulsion layers were overcoated with a protective layer. Amounts of coating solutions were the same in all cases in the emulsion layer as well as in the protective layer.
• Demineralised water was added in order to reach a concentration corresponding to about 200 g of silver nitrate pro liter of coating solution.
• a protective coating composition was prepared containing per liter the following ingredients in demineralised water:
• Ratios of gelatin to silver nitrate for all emulsions were approximately 0.3 for all emulsions.
• the coated materials were exposed with with green light of 540 nm during 0.1 seconds using a continuous wedge and were processed during the 38 seconds processing cycle in the processing machine CURIX HT530 (Agfa-Gevaert trademarked name) with the following time (in seconds) and temperature (in °C) characteristics: loading 0.2 sec. developing 9.3 sec. 35°C in developer described below cross-over 1.4 sec. rinsing 0.9 sec. cross-over 1.5 sec. fixing 6.6 sec. 35°C in fixer described below cross-over 2.0 sec. rinsing 4.4 sec. 20°C cross-over 4.6 sec. drying 6.7 sec. total 37.6 sec. ⁇
• ammonium thiosulfate (78 % solution) 661 grams sodium sulphite 54 grams boric acid 25 grams sodium acetate-trihydrate 70 grams acetic acid 40 grams water to make 1 liter pH adjusted with acetic acid to 5.30 at 25°C
• ammonium thiosulfate (78 % solution) 661 grams sodium sulphite 54 grams boric acid 25 grams sodium acetate-trihydrate 70 grams acetic acid 40 grams water to make 1 liter pH adjusted with acetic acid to 5.30 at 25°C
• a pH of 5.25 was measured at 25°C.
• the sensitivity S was determined at a density of 1 above fog and support density.
• Emulsion 6 (invention):
• the initial UAg measured vs. a silver/silver chloride reference electrode was adjusted at -34 mV before starting the precipitation.
• a nucleation step was performed by introducing solution A and solution B1 simultaneously in dispersion medium C both at a flow rate of 60 ml/min during 30 seconds. After a physical ripening time of 20 min 100 ml of a 15 % solution of 'Kieselsol 500' and 30 ml of a 5 % solution of the same phosphonium compound, together with 320 ml of demineralised water, were added and the pH value was adjusted to a value of 3.0. The solution was stirred for another 5 minutes.
• a growth step was performed by introducing by a double jet during 31 minutes 48 seconds solution A starting at a flow rate of 2.5 ml/min and linearly increasing the flow rate to an end value of 7 ml/min, and solution B1 at an increasing flow rate in order to maintain a constant UAg-value of + 10 mV. After a physical ripening time of 5 minutes and 30 seconds a second growth step was performed.
• This second growth step was performed by introducing by a double jet during 5 minutes 54 seconds solution A starting at a flow rate of 2.5 ml/min and after that time linearly increasing the flow rate to an end value of 12.5 ml/min during 41 minutes 22 seconds, and solution B2 at an increasing flow rate in order to maintain a constant UAg-value of + 10 mV.
• Emulsion 7 (invention):
• Emulsion 6 Same preparation as for Emulsion 6, except for the presence in the 2.5 l of a dispersion medium (C) of 67 ml of 15 % silica sol 'Kieselsol 500' (trademarked product of Bayer AG) and 40 ml of a 5 % solution of co-stabilising phosphonium compound and addition after the first physical ripening time of 20 min, following the nucleation step, of 133 ml of a 15 % solution of 'Kieselsol 500' and 80 ml of a 5 % solution of the same phosphonium compound, together with 237 ml of demineralised water, were added and the pH value was adjusted to a value of 3.0.
• C dispersion medium
• 67 ml of 15 % silica sol 'Kieselsol 500' trademarked product of Bayer AG
• 40 ml of a 5 % solution of co-stabilising phosphonium compound addition after the first physical ripening time of 20 min, following
• Emulsion 8 (invention):
• Emulsion 6 Same preparation as for Emulsion 6, except for the presence in the 2.5 l of a dispersion medium (C) of 33 ml of 15 % silica sol 'Kieselsol 500' (trademarked product of Bayer AG) and 15 ml of a 5 % solution of co-stabilising phosphonium compound and addition after the first physical ripening time of 20 min, following the nucleation step, of 67 ml of a 15 % solution of 'Kieselsol 500' and 30 ml of a 5 % solution of the same phosphonium compound, together with 353 ml of demineralised water, were added and the pH value was adjusted to a value of 3.0.
• C dispersion medium
• the sizes of the crystals are comparable.
• the ratio values of d EM are situated around a value of about 0.8, which is within the range for the inventive emulsions from Example 1, wherein the thickness ratio of triangular tabular crystals to hexagonal tabular crystals is from 1.3 to 0.7.

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• 1996
  • 1996-07-11 EP EP96201956A patent/EP0754964A1/de not_active Withdrawn

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