EP1186949A1 - Matériaux photothermographiques - Google Patents

Matériaux photothermographiques Download PDF

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Publication number
EP1186949A1
EP1186949A1 EP01000386A EP01000386A EP1186949A1 EP 1186949 A1 EP1186949 A1 EP 1186949A1 EP 01000386 A EP01000386 A EP 01000386A EP 01000386 A EP01000386 A EP 01000386A EP 1186949 A1 EP1186949 A1 EP 1186949A1
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EP
European Patent Office
Prior art keywords
silver
silver salt
salt
water
aqueous dispersion
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EP01000386A
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German (de)
English (en)
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EP1186949B1 (fr
Inventor
Herman c/o AGFA-GEVAERT Uytterhoeven
Johan c/o Agfa-Gevaert Loccufier
Yvan c/o AGFA-GEVAERT Gilliams
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Agfa Gevaert NV
Agfa Gevaert AG
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Agfa Gevaert NV
Agfa Gevaert AG
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Priority to EP20010000386 priority Critical patent/EP1186949B1/fr
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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
    • G03C1/494—Silver salt compositions other than silver halide emulsions; Photothermographic systems ; Thermographic systems using noble metal compounds
    • G03C1/498—Photothermographic systems, e.g. dry silver
    • G03C1/49836—Additives
    • G03C1/49845—Active additives, e.g. toners, stabilisers, sensitisers

Definitions

  • the present invention relates to an aqueous dispersion of a substantially light-insensitive organic silver salt and a photosensitive silver halide and a photothermographic recording material prepared therefrom.
  • EP-A 754 969 discloses a process for producing a suspension of particles containing a substantially light-insensitive silver salt of an organic carboxylic acid, comprising simultaneous metered addition of an aqueous solution or suspension of an organic carboxylic acid or its salt; and an aqueous solution of a silver salt to an aqueous liquid, wherein the metered addition of the aqueous solution or suspension of the organic carboxylic acid or its salt; and/or the aqueous solution of the silver salt is regulated by the concentration of silver ions or the concentration of anions of the silver salt in the aqueous liquid.
  • excess dissolved silver ions are converted into at least one silver salt and the particles of substantially light-insensitive silver salt of an organic carboxylic acid are produced in the presence of silver halide particles.
  • EP-A 851 285 discloses a process for producing an aqueous dispersion I containing particles including a substantially light-insensitive organic heavy metal salt A with a solubility in 1 L of water of less than 10 -2 g at 20°C comprising the steps of: (i) producing an aqueous dispersion II containing particles including a salt B with a solubility in 1 L of water between 15g and 0.01g at 20°C; and (ii) converting the salt B in the particles of the aqueous dispersion II into the organic heavy metal salt A, characterized in that the organic heavy metal salt A and the salt B have a common cation.
  • a principal problem in developing photothermographic recording materials with photo-addressable thermally developable elements coated from aqueous media is their lower photosensitivity than photothermographic recording materials with photo-addressable thermally developable elements coated from solvent media.
  • a means is therefore necessary to boost the photosensitivity of photo-addressable thermally developable elements coated from aqueous media, so that the environmental and economic benefits of coating from aqueous media can be realized.
  • a process for producing an aqueous dispersion comprising in the following order the steps of: (i) preparing a dispersion of photosensitive silver halide and a binder or a surfactant in an aqueous medium; (ii) adding a first silver salt to the dispersion prepared in step (i); and (iii) adding a second silver salt to the dispersion prepared in step (ii), wherein the aqueous dispersion is substantially free of a water-soluble metal or ammonium salt of an aliphatic carboxylic acid with greater than 12 carbon atoms, the first silver salt is a substantially light-insensitive and substantially water-insoluble silver salt of an organic carboxylic acid, and the second silver salt has a water-solubility greater than 0.1 g in 1 L of water at 20°C.
  • a process for producing an aqueous dispersion comprising in the following order the steps of: (i) preparing a dispersion of photosensitive silver halide and a binder or a surfactant in an aqueous medium; (ii) adding a second silver salt to the dispersion prepared in step (i); and (iii) adding a first silver salt to the dispersion prepared in step (ii), wherein the aqueous dispersion is substantially free of a water-soluble metal or ammonium salt of an aliphatic carboxylic acid with greater than 12 carbon atoms, the first silver salt is a substantially light-insensitive and substantially water-insoluble silver salt of an organic carboxylic acid, and the second silver salt has a water-solubility greater than 0.1 g in 1 L of water at 20°C.
  • a second silver salt with a water-solubility greater than 0.1g/L water at 20°C for increasing the sensitivity of a photothermographic recording material thermally developable under substantially water-free conditions
  • the photothermographic recording material having a photo-addressable thermally developable element, the photo-addressable thermally developable element containing a first silver salt, a reducing agent therefor in thermal working relationship therewith and a binder, wherein the aqueous dispersion is substantially free of a water-soluble metal or ammonium salt of an aliphatic carboxylic acid with greater than 12 carbon atoms and the first silver salt is a substantially light-insensitive and substantially water-insoluble silver salt of an organic carboxylic acid.
  • a photothermographic recording material thermally developable under substantially water-free conditions comprising a support and a photo-addressable thermally developable element, the photo-addressable thermally developable element fulfilling two requirements:
  • a process for preparing a photothermographic recording material thermally developable under substantially water-free conditions comprising a support and a photo-addressable thermally developable element and the photo-addressable thermally developable element containing a photosensitive silver halide, a first silver salt, a reducing agent therefor in thermal working relationship therewith and a binder, comprising the steps of: (i) coating the above-described aqueous dispersion onto a support; and (ii) drying the layer formed in step (i) .
  • aqueous for the purposes of the present invention means containing at least 60% by volume of water, preferably at least 80% by volume of water, and optionally containing water-miscible organic solvents such as alcohols e.g. methanol, ethanol, 2-propanol, butanol, iso-amyl alcohol, octanol, cetyl alcohol etc.; glycols e.g. ethylene glycol; glycerine; N-methyl pyrrolidinone; methoxypropanol; and ketones e.g. 2-propanone and 2-butanone etc.
  • alcohols e.g. methanol, ethanol, 2-propanol, butanol, iso-amyl alcohol, octanol, cetyl alcohol etc.
  • glycols e.g. ethylene glycol; glycerine; N-methyl pyrrolidinone; methoxypropanol
  • ketones e.g. 2-propanone and
  • Substantially free of a water-soluble metal or ammonium salt of an aliphatic carboxylic acid with greater than 12 carbon atoms means that a water-soluble metal or ammonium salt of an aliphatic carboxylic acid with greater than 12 carbon atoms is not intentionally present and if present is only present in trace quantities.
  • water-soluble salt means salts with a solubility in water at 20°C of at least 2mg/L.
  • metal or ammonium salt of an aliphatic carboxylic acid with greater than 12 carbon atoms includes lithium, potassium, sodium, rubidium, caesium and ammonium salts of aliphatic carboxylic acids, such as behenic and stearic acid, and mixtures thereof.
  • Substantially light-insensitive means not intentionally light sensitive and resistant to darkening upon exposure.
  • Substantially water-insoluble means a solubility in water at 20°C of less than 2mg/L.
  • S is defined as that exposure in mJ/m 2 at which the photothermographic recording material attained an optical density of 1.0 above Dmin.
  • the UAg of an aqueous liquid is defined in this specification as the potential difference between a silver electrode (of 99.99% purity) in the aqueous liquid and a reference electrode consisting of a Ag/AgCl-electrode in 3M KCl solution at room temperature connected with the liquid via a salt bridge consisting of a 10% KMO 3 salt solution.
  • heat solvent in this specification is meant a non-hydrolyzable organic material which is in solid state in the recording layer at temperatures below 50°C but becomes a plasticizer for the recording layer in the heated region and/or liquid solvent for at least one of the redox-reactants, e.g. the reducing agent for the first silver salt, at a temperature above 60°C.
  • thermally developable under substantially water-free conditions means heating at a temperature of 80° to 250°C under conditions in which the reaction system is approximately in equilibrium with water in the air, and water for inducing or promoting the reaction is not particularly or positively supplied from the exterior of the thermographic recording material.
  • a condition is described in T. H. James, "The Theory of the Photographic Process, Fourth Edition, Macmillan 1977", page 374.
  • the first silver salt is a substantially light-insensitive and substantially water-insoluble silver salt of an organic carboxylic acid having as its organic group: aryl, aralkyl, alkaryl or alkyl groups.
  • Aliphatic carboxylic acids known as fatty acids, wherein the aliphatic carbon chain has preferably at least 12 C-atoms are preferred e.g. silver laurate, silver palmitate, silver stearate, silver hydroxystearate, silver oleate, silver behenate and silver arichidate, which silver salts are also called "silver soaps".
  • silver benzoate and silver salts of organic carboxylic acids described in Research Disclosure 17029, but excluding silver salts of organic carboxylic acids substituted with a heterocyclic thione group as disclosed in Research Disclosure 12542 and US 3,785,830, may also be used to produce a thermally developable silver image.
  • Combinations of the first silver salts may also be used in the present invention.
  • Aqueous dispersions of first silver salts or mixtures thereof can be produced as described in US 5,891,616 and EP-A 848286 and US 3,839,049.
  • the second silver salt in the aqueous dispersion of the present invention has a solubility in water at 20°C of greater than 0.1g/L, with greater than 1g/L being preferred.
  • Suitable second silver salts in the aqueous dispersion of the present invention include silver nitrate, silver acetate, silver propionate, silver butyrate, silver isobutyrate, silver tartrate, silver salicylate, silver malonate, silver succinate, silver lactate and silver oxalate.
  • solubility in water at 20°C in g/L water silver nitrate 2150 silver fluoride 1800 (at 25°C) silver dithionate 500 (at 16°C) silver acetate# 10.4 silver propionate# 8.4 silver sulphate 7.7 (at 18°C) silver butyrate# 4.9 silver metaphosphate 3.2 silver benzoate 2.17 silver tartrate# 2.01 (at 18°C) silver nitrite 4.2 (at 25°C) silver selenate 1.2 silver salicylate 0.8 (at 18°C) silver hyponitrite 0.75 (at 13°C) silver malonate# 0.57 silver tungstate 0.5 (at 15°C) silver succinate# 0.18 (at 18°C) silver lactate# Silver salts marked with # are themselves photosensitive although no deterioration in the level of image background has been observed upon adding the second silver salt, when such salts are used.
  • the photosensitive silver halide used in the present invention may be employed in a range of 0.1 to 100 mol percent; preferably, from 0.2 to 80 mol percent; particularly preferably from 0.3 to 50 mol percent; especially preferably from 0.5 to 35 mol %; and especially from 1 to 12 mol % of substantially light-insensitive organic silver salt.
  • the silver halide may be any photosensitive silver halide such as silver bromide, silver iodide, silver chloride, silver bromoiodide, silver chlorobromoiodide, silver chlorobromide etc.
  • the silver halide may be in any form which is photosensitive including, but not limited to, cubic, orthorhombic, tabular, tetrahedral, octagonal etc. and may have epitaxial growth of crystals thereon.
  • the silver halide used in the present invention may be employed without modification. However, it may be chemically sensitized with a chemical sensitizing agent such as a compound containing sulphur, selenium, tellurium etc., or a compound containing gold, platinum, palladium, iron, ruthenium, rhodium or iridium etc., or a combination thereof.
  • a chemical sensitizing agent such as a compound containing sulphur, selenium, tellurium etc., or a compound containing gold, platinum, palladium, iron, ruthenium, rhodium or iridium etc., or a combination thereof.
  • the grain size of the silver halide particles can be determined by the Moeller Teller method in the sample containing silver halide particles is sedimented upon a filter paper, which is submerged in electrolyte together with a negative platinum needle-shaped electrode and a reference electrode.
  • the silver halide particles on the filter paper are slowly scanned individually with the needle-shaped electrode, whereupon the silver halide grains are individually electrochemically reduced at the cathode.
  • This electrochemical reduction is accompanied by a current pulse, which is registered as a function of time and integrated to give the charge transfer Q for the electrochemical reduction of the silver halide particle, which is proportional to its volume. From their volume the equivalent circular grain diameter of each grain can be determined and therefrom the average particle size and size distribution.
  • a process for producing an aqueous dispersion comprising: preparing a dispersion of photosensitive silver halide and a binder or a surfactant in an aqueous medium; and subsequently either (a) adding a first silver salt to the silver halide dispersion and then adding a second silver salt; or (b) adding the second silver salt to the silver halide dispersion and then adding the first silver salt, wherein the aqueous dispersion is substantially free of a water-soluble metal or ammonium salt of an aliphatic carboxylic acid with greater than 12 carbon atoms, the first silver salt is a substantially light-insensitive and substantially water-insoluble silver salt of an organic carboxylic acid, and the second silver salt has a water-solubility greater than 0.1 g in 1 L of water at 20°C.
  • the silver behenate not be prepared in the presence of silver halide.
  • Such processes exclude the synthesis process of the first silver salt as can be seen from the absence from the aqueous dispersion of a metal or ammonium salt of an aliphatic carboxylic acid with greater than 12 carbon atoms.
  • the binder used for dispersing the photosensitive silver halide may a water-dispersible or a water-soluble binder.
  • Suitable water-soluble binders are: polyvinyl alcohol, polyacrylamide, polymethacrylamide, polyacrylic acid, polymethacrylic acid, polyethyleneglycol, polyvinylpyrrolidone, proteinaceous binders such as gelatine, modified gelatines such as phthaloyl gelatine, polysaccharides, such as starch, gum arabic and dextran and water-soluble cellulose derivatives.
  • the surfactant used for dispersing the photosensitive silver halide is preferably a anionic or non-ionic surfactant, with anionic sulfonate surfactants being particularly preferred.
  • UAg being the potential difference between a silver electrode (of ⁇ 99.99% purity) in the aqueous liquid and a reference electrode consisting of a Ag/AgCl-electrode in 3M KCl solution at room temperature connected with the liquid via a salt bridge consisting of a 10% KNO 3 salt solution.
  • the UAg increase due to adding the second silver salt is preferably at least 50mV, with at least 100mV being particularly preferred.
  • UAg there is an decrease in UAg between step (ii) and step (iii), UAg being the potential difference between a silver electrode (of ⁇ 99.99% purity) in the aqueous liquid and a reference electrode consisting of a Ag/AgCl-electrode in 3M KCl solution at room temperature connected with the liquid via a salt bridge consisting of a 10% KNO 3 salt solution.
  • aqueous ammonia is added such that the pH of the aqueous dispersion does not exceed a value of 9.0. At higher pH-values silver hydroxide and silver oxide are formed, which cause increased image background (Dmin) levels.
  • the second silver salt can be added as an aqueous solution, dissolved in a small quantity of water-miscible organic solvent or as a slurry in water, although in the latter case the particles of second silver salt must dissolve during the production of the aqueous emulsion.
  • the water-solubility of the second silver salt mainly influences the preparation time of the aqueous dispersion, since the increase in photosensitivity is dependent upon ionic dissociation of the second silver salt in the aqueous medium.
  • the water-solubility of the second silver salt is therefore greater than 0.1g in 1 L of water at 20°C.
  • the binder or surfactant is necessary to keep the substantially light-insensitive and water insoluble organic silver salt and the photosensitive silver halide in suspension.
  • the second silver salt is selected from the group consisting of silver nitrate, silver acetate, silver lactate and silver sulphate.
  • the present invention provides an aqueous dispersion obtainable by the above-mentioned processes for preparing an aqueous dispersion.
  • the quantity of second silver salt added is at least 1 mol% with respect to the quantity of the photosensitive silver halide and preferably at least 15 mol% with respect to the quantity of the photosensitive silver halide.
  • the quantity of second silver salt is preferably also less than 80 mol% with respect to the quantity of the photosensitive silver halide.
  • the particle size of the photosensitive silver halide is preferably between 70 and 100 nm.
  • the aqueous dispersion further contains a reducing agent for the first silver salt.
  • Suitable organic reducing agents for the reduction of the first silver salt particles are organic compounds containing at least one active hydrogen atom linked to O, N or C, such as is the case with: aromatic di- and tri-hydroxy compounds; aminophenols; METOLTM; p-phenylene-diamines; alkoxynaphthols, e.g. 4-methoxy-1-naphthol described in US 3,094,41; pyrazolidin-3-one type reducing agents, e.g.
  • PHENIDONETM pyrazolin-5-ones; indan-1,3-dione derivatives; hydroxytetrone acids; hydroxytetronimides; hydroxylamine derivatives such as for example described in US 4,082,901; hydrazine derivatives; and reductones e.g. ascorbic acid; see also US 3,074,809, 3,080,254, 3,094,417 and 3,887,378.
  • Particularly suitable reducing agents are sterically hindered phenols, bisphenols, sulfonamidophenols and those described in WO97/04357.
  • Combinations of reducing agents may also be used that on heating become reactive partners in the reduction of the substantially light-insensitive silver salt of an organic carboxylic acid.
  • combinations of sterically hindered phenols with sulfonyl hydrazide reducing agents such as disclosed in US 5,464,738; trityl hydrazides and formyl-phenyl-hydrazides such as disclosed in US 5,496,695; trityl hydrazides and formyl-phenyl-hydrazides with diverse auxiliary reducing agents such as disclosed in US 5,545,505, US 5,545,507 and US 5,558,983; acrylonitrile compounds as disclosed in US 5,545,515 and US 5,635,339; and 2-substituted malonodialdehyde compounds as disclosed in US 5,654,130
  • the photothermographic recording material thermally developable under substantially water-free conditions of the present invention comprises a support and a photo-addressable thermally developable element, which fulfils two requirements: (i) it contains a first silver salt, a reducing agent therefor in thermal working relationship therewith, a photosensitive silver halide and a binder; and (ii) it comprises a layer obtainable by coating an aqueous dispersion, according to the present invention.
  • the aqueous dispersion contains a binder or a surfactant, a first silver salt, a photosensitive silver halide, a second silver salt and optionally contains a reducing agent for the first silver salt, a spectral sensitizer, a supersensitizer, one or more stabilizers and a binder.
  • the photo-addressable thermally developable element may comprise a single layer, i.e. produced with the aqueous dispersion according to the present invention, or may comprise more than one layer, one of which is produced with the aqueous dispersion and the others containing the other ingredients necessary for image formation e.g. a reducing agent for the first silver salt, a binder, a toning agent and one or more stabilizers.
  • the photosensitive silver halide should be in catalytic association with the substantially light-insensitive silver salt of an organic carboxylic acid
  • the spectral sensitizer should be optionally together with a supersensitizer in intimate sensitizing association with the silver halide particles
  • the other ingredients active in the thermal development process or pre- or post-development stabilization of the element should be in the same layer or in other layers with the proviso that the organic reducing agent and the toning agent, if present, should be in thermal working relationship with the substantially light-insensitive silver salt of an organic carboxylic acid i.e. during the thermal development process the reducing agent and the toning agent, if present, are able to diffuse to the substantially light-insensitive silver salt of an organic carboxylic acid.
  • the photo-addressable thermally developable element may also be coated with a protective layer.
  • the film-forming binder for use in the aqueous dispersion and photo-addressable thermally developable element of the present invention may a water-dispersible or a water-soluble binder.
  • Suitable water-soluble film-forming binders are: polyvinyl alcohol, polyacrylamide, polymethacrylamide, polyacrylic acid, polymethacrylic acid, polyethyleneglycol, polyvinylpyrrolidone, proteinaceous binders such as gelatine, modified gelatines such as phthaloyl gelatine, polysaccharides, such as starch, gum arabic and dextran and water-soluble cellulose derivatives.
  • Suitable water-dispersible binders are any water-insoluble polymers e.g. water-insoluble cellulose derivatives, polyurethanes, polyesters polycarbonates and polymers derived from ⁇ , ⁇ -ethylenically unsaturated compounds such as after-chlorinated polyvinyl chloride, partially hydrolyzed polyvinyl acetate, polyvinyl acetals, preferably polyvinyl butyral, and homopolymers and copolymers produced using monomers selected from the group consisting of: vinyl chloride, vinylidene chloride, acrylonitrile, acrylamides, methacrylamides. methacrylates, acrylates, methacrylic acid, acrylic acid, vinyl esters, styrenes, dienes and alkenes; or mixtures thereof.
  • water-insoluble polymers e.g. water-insoluble cellulose derivatives, polyurethanes, polyesters polycarbonates and polymers derived from ⁇ , ⁇ -ethylenically uns
  • Preferred water-dispersible binders are water-dispersible film-forming polymers with covalently bonded ionic groups selected from the group consisting of sulfonate, sulfinate, carboxylate, phosphate, quaternary ammonium, tertiary sulfonium and quaternary phosphonium groups. Further preferred water-dispersible binders are water-dispersible film-forming polymers with covalently bonded moieties with one or more acid groups.
  • Water-dispersible binders with crosslinkable groups e.g. epoxy groups, aceto-acetoxy groups and crosslinkable double bonds are also preferred.
  • Preferred water-dispersible binders for use in the photo-addressable thermally developable element of the present invention are polymer latexes as disclosed in WO 97/04355.
  • binders or mixtures thereof may be used in conjunction with waxes or "heat solvents” also called “thermal solvents” or “thermosolvents” improving the reaction speed of the redox-reaction at elevated temperature.
  • the aqueous dispersion or photo-addressable thermally developable element of the photothermographic recording material may contain a spectral sensitizer, optionally together with a supersensitizer, for the silver halide appropriate for the wavelength of the light source which may in the near UV, visible, e.g. 630nm, 670nm etc., or IR, parts of spectrum.
  • the silver halide may be spectrally sensitized with various known dyes including cyanine, merocyanine, styryl, hemicyanine, oxonol, hemioxonol and xanthene dyes optionally, particularly in the case of sensitization to infra-red radiation, in the presence of a so-called supersensitizer.
  • various known dyes including cyanine, merocyanine, styryl, hemicyanine, oxonol, hemioxonol and xanthene dyes optionally, particularly in the case of sensitization to infra-red radiation, in the presence of a so-called supersensitizer.
  • Useful cyanine dyes include those having a basic nucleus, such as a thiazoline nucleus, an oxazoline nucleus, a pyrroline nucleus, a pyridine nucleus, an oxazole nucleus, a thiazole nucleus, a selenazole nucleus and an imidazole nucleus.
  • a basic nucleus such as a thiazoline nucleus, an oxazoline nucleus, a pyrroline nucleus, a pyridine nucleus, an oxazole nucleus, a thiazole nucleus, a selenazole nucleus and an imidazole nucleus.
  • Useful merocyanine dyes which are preferred include those having not only the above described basic nuclei but also acid nuclei, such as a thiohydantoin nucleus, a rhodanine nucleus, an oxazolidinedione nucleus, a thiazolidinedione nucleus, a barbituric acid nucleus, a thiazolinone nucleus, a malononitrile nucleus and a pyrazolone nucleus.
  • acid nuclei such as a thiohydantoin nucleus, a rhodanine nucleus, an oxazolidinedione nucleus, a thiazolidinedione nucleus, a barbituric acid nucleus, a thiazolinone nucleus, a malononitrile nucleus and a pyrazolone nucleus.
  • imino groups or carboxyl groups are particularly effective.
  • the aqueous dispersion or photo-addressable thermally developable element may further include a supersensitizer.
  • Preferred supersensitizers are selected from the group of compounds consisting of: mercapto-compounds, disulfide-compounds, stilbene compounds, organoborate compounds and styryl compounds.
  • the aqueous dispersion or photo-addressable thermally developable element according to the present invention may contain one or more toning agents.
  • the toning agents should be in thermal working relationship with the first silver salt and reducing agent therefor during thermal processing.
  • stabilizers and antifoggants such as phenyl tribromomethyl sulphone, 4- methyl phthalic acid and 2-mercapto-4-heptyl-oxadiazole may be incorporated into the photo-addressable thermally developable elements or the aqueous dispersion of the present invention.
  • the support for the photothermographic recording material according to the present invention may be transparent, translucent or opaque and is preferably a thin flexible carrier made e.g. from paper, polyethylene coated paper or transparent resin film, e.g. made of a cellulose ester, e.g. cellulose triacetate, polypropylene, polycarbonate or polyester, e.g. polyethylene terephthalate.
  • the support may be in sheet, ribbon or web form.
  • the support may be subbed with a subbing layer. It may also be made of an opacified resin composition.
  • the photothermographic recording materials used in the present invention may also contain antihalation or acutance dyes which absorb light which has passed through the photosensitive thermally developable photographic material, thereby preventing its reflection. Such dyes may be incorporated into the photo-addressable thermally developable element or in any other layer of the photothermographic material of the present invention.
  • an antistatic layer is applied to an outermost layer.
  • thermographic and photothermographic recording materials of the present invention may contain anionic, non-ionic or amphoteric surfactants, with anionic and non-ionic surfactants preferred as disclosed in WO 97/04356.
  • Suitable dispersants are natural polymeric substances, synthetic polymeric substances and finely divided powders, for example finely divided non-metallic inorganic powders such as silica.
  • any layer of the photothermographic recording materials of the present invention may proceed by any coating technique e.g. such as described in Modern Coating and Drying Technology, edited by Edward D. Cohen and Edgar B. Gutoff, (1992) VCH Publishers Inc., 220 East 23rd Street, Suite 909 New York, NY 10010, USA, hereby incorporated by reference.
  • the present invention also provides a process for preparing a photothermographic recording material.
  • thermographic recording material is heated at a temperature of at least 35°C for at least 3 days with a temperature of at least 45°C being particularly preferred. Furthermore, the temperature is preferably less than 50°C.
  • the period is preferably at least 1 week and the heating is preferably carried out at a relative humidity between 10 and 75% and particularly preferably between 15 and 70%. Especially preferred is heating in the dark for 7 days at 45°C and 70% relative humidity.
  • Photothermographic recording materials may be exposed with radiation of wavelength between an X-ray wavelength and a 5 microns wavelength with the image either being obtained by pixel-wise exposure with a finely focused light source, such as a CRT light source; a UV, visible or IR wavelength laser, such as a He/Ne-laser or an IR-laser diode, e.g. emitting at 780nm, 830nm or 850nm; or a light emitting diode, for example one emitting at 659nm; or by direct exposure to the aspect itself or an image therefrom with appropriate illumination e.g. with UV, visible or IR light.
  • a finely focused light source such as a CRT light source
  • a UV, visible or IR wavelength laser such as a He/Ne-laser or an IR-laser diode, e.g. emitting at 780nm, 830nm or 850nm
  • a light emitting diode for example one
  • any sort of heat source can be used that enables the recording materials to be uniformly heated to the development temperature in a time acceptable for the application concerned e.g. contact heating, radiative heating, microwave heating etc.
  • Photothermographic recording materials according to the present invention may be used for both the production of transparencies, for example in the medical diagnostic field in which black-imaged transparencies are widely used in inspection techniques operating with a light box, reflection type prints, for example in the hard copy graphics field and in microfilm applications.
  • the support will be transparent or opaque, i.e. having a white light reflecting aspect.
  • the base may be colourless or coloured, e.g. with a blue colour for medical diagnostic applications.
  • the type 02 silver halide emulsion consisting of 11.44% by weight of silver halide particles consisting of 97mol% silver bromide and 3mol% silver iodide with a weight average particle size of 70nm as measured with the Moeller Teller method (see above for details) and 5.17% by weight of R16875 as dispersing agent in deionized water was prepared using conventional silver halide preparation techniques at 50.5°C such as described, for example, in T.H. James, "The Theory of the Photographic Process, Fourth Edition, Macmillan Publishing Co. Inc., New York (1977)", Chapter 3, pages 88-104.
  • Types 01 and 03-15 photosensitive silver halide were prepared as described above except as indicated in Table 1 and in the notes referred to therein.
  • the aqueous silver behenate dispersion obtained contained 8.15% by weight of silver behenate and 2.78% by weight of Surfactant 1 and was subsequently desalted and concentrated using ultrafiltration to an aqueous dispersion containing 22.37% by weight of silver behenate.
  • UAg-1 After stirring for 1 hour at 40°C a UAg measurement was carried out (UAg-1) then 206.6g of the above-described silver behenate dispersion was added together with 2.4g of 1N nitric acid and after a further 20 minutes stirring at 40°C a second UAg measurement (UAg-2) was carried out.
  • An antihalation layer dispersion was prepared by dissolving 62.5g of K7598 in 1L of deionized water at 40°C. The following ingredients were then added to the resulting gelatin solution: 14.5g of a 10% by aqueous weight solution of ANTIHALO 01, 8g of a 10% by weight aqueous dispersion of LATEX 01, 42g of a 20% by weight aqueous dispersion of KIESELSOL 300F and finally the pH was adjusted to 6 before doctor-blade coating to a wet-layer thickness of 45 ⁇ m on one side of a 100 ⁇ m poly(ethylene terephthalate) support subbed on both sides and drying at 25°C for 5 minutes.
  • thermosensitive element A solution for the first layer of the thermosensitive element was then prepared by dissolving 42.5g of K7598 in 1928.2g of deionized water at 40°C and then adding the following ingredients with stirring: 8.7g of STABI 02, 179.1g of a STABI 03-dispersion (consisting of 17.5% by weight of STABI 03, 10% by weight of K7598 and 1% by weight of Surfactant Nr. 1), 6g of 1-phenyl-5-mercaptotetrazole dissolved in 227.3g of methanol and 17.4g of a 10% solution of Surfactant Nr. 3.
  • the side of the support not coated with the antihalation layer was then coated with the solution for the first layer of the thermosensitive element to a wet layer thickness of 50 ⁇ m to produce after drying at 25°C for 5 minutes the first layer of the thermosensitive element.
  • thermosensitive element was then overcoated with the above-described aqueous dispersion to a wet layer thickness of 100 ⁇ m to form after drying at 25°C for 5 minutes the second layer of the thermosensitive element.
  • thermosensitive element was overcoated with a solution of 57g of K7598 in 2560g of deionized water to which 78g of a 5% by weight solution of Surfactant Nr. 4 had been added to a wet layer thickness of 50 ⁇ m to form after drying at 25°C for 5 minutes a protective layer.
  • the photothermographic recording materials of INVENTIVE EXAMPLES 1 to 5 and COMPARATIVE EXAMPLE 1 were first exposed to a He-Ne laser (632.8 nm) through a grey scale wedge to vary the exposure of the film and then heated for 20s at 100°C to produce a wedge image.
  • the print density variation in the wedge image was determined with a MACBETH TD903 densitometer with a visual filter giving the dependence of optical density upon exposure.
  • Photothermographic evaluation was carried out on freshly coated photothermographic recording materials and also after being subjected to one or more of the following tests to determine the changes in background density ⁇ Dmin and in S, ⁇ S:
  • the photothermographic recording materials of INVENTION EXAMPLES 1 to 5 and COMPARATIVE EXAMPLE 1 were all carried out with type 01 silver halide.
  • Addition of silver nitrate as the second silver salt in concentrations between 3.58 mol% (INVENTION EXAMPLE 1) and 44.8 mol% (INVENTION EXAMPLE 5) with respect to silver halide produced a significant reduction in S-values compared with S-value of 631mJ/m 2 exhibited by the photothermographic recording material of COMPARATIVE EXAMPLE 1 in which no silver nitrate had been added during the preparation of the aqueous dispersion i.e.
  • Photothermographic recording materials of INVENTION EXAMPLES 1 to 5 thus requiring a lower exposure to obtain the same density and hence exhibiting significantly higher photosensitivity.
  • Photothermographic recording materials in which silver nitrate quantities between 35 and 45 mol% with respect to silver halide had been added (see INVENTION EXAMPLES 4 and 5) exhibited the lowest S-values (i.e. the highest photosensitivities) and the lowest Dmin values for fresh materials.
  • the photothermographic recording materials of INVENTION EXAMPLES 10 to 12 and COMPARATIVE EXAMPLE 2 were all carried out with type 06 silver halide. Addition of silver nitrate as the second silver salt in concentrations between 26.8 mol% (INVENTION EXAMPLE 10) and 71.6 mol% (INVENTION EXAMPLE 12) with respect to silver halide, produced a significant reduction in S-values compared with the S-value of 446mJ/m 2 exhibited by the photothermographic recording material of COMPARATIVE EXAMPLE 2 in which no silver nitrate had been added during the preparation of the aqueous dispersion i.e. from 446 to 79-178mJ/m 2 , the photothermographic recording materials of INVENTION EXAMPLES 10 to 12 requiring a lower exposure to obtain the same density and hence exhibiting significantly higher photosensitivities.
  • Photothermographic recording materials with silver iodobromide doped with Ir 4+ optionally with Cu 2+ or Fe 3+ for a similar grain size exhibited similar photosensitivities, but with a significantly lower Dmin (see the results for INVENTION EXAMPLES 4 and 6 to 8).
  • the photothermographic recording material of INVENTION EXAMPLE 36 was produced as described for INVENTION EXAMPLE 4, details being given in Table 9. Photothermographic evaluation was carried out as described above for INVENTION EXAMPLES 1 to 5 and COMPARATIVE EXAMPLE 1 and also after they were subjected to different ageing regimes to determine the changes in background density ⁇ Dmin and in S, ⁇ S. The Dmin and S-values for the fresh photothermographic recording materials C and D are also given Table 9. Invention example nr.
  • Ageing regimes i) and ii) showed that no stabilization of Dmin was achieved after subjection for 7 days in the dark at 20°C and 45% relative humidity in ageing test i), despite an increase of 0.64 in Dmin, as evidenced by the further 0.95 increase in Dmin upon a further 35 days in the dark at 20°C and ca. 45% relative humidity [ageing test ii)].
  • the photothermographic recording materials of INVENTION EXAMPLES 37 and 38 were produced as described for INVENTION EXAMPLE 11 except that the aqueous emulsions were prepared by mixing the same quantities of ingredients in a different order.
  • the preparation of the aqueous emulsion of INVENTION EXAMPLE 37 differed from that of INVENTION EXAMPLE 11 in that the silver halide dispersion was mixed with the silver behenate dispersion before the 4.19 mmol AgNO 3 was added and the nitric acid was not added simultaneously with the silver behenate dispersion, but after the addition of the silver nitrate.
  • the UAg was determined after the nitric acid was added to be 417 mV, which is similar to the Uag-2 value found for INVENTION EXAMPLE 11.
  • the preparation of the aqueous emulsion of INVENTION EXAMPLE 38 differed from that of INVENTION EXAMPLE 11 in that the silver nitrate solution was not added before the addition of silver behenate dispersion, but after the addition of the solution of STABI 01 in methanol.
  • the UAg was determined after mixing the silver halide, silver behenate and nitric acid to be 291 mV.
  • aqueous emulsions of INVENTION EXAMPLES 37 and 38 are both produced by adding the silver nitrate solution after mixing the silver halide and silver behenate dispersions.
EP20010000386 2000-09-11 2001-08-17 Matériaux photothermographiques Expired - Lifetime EP1186949B1 (fr)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3615533A (en) * 1968-03-11 1971-10-26 Eastman Kodak Co Heat and light sensitive layers containing hydrazones
EP0715209A2 (fr) * 1994-11-25 1996-06-05 Fuji Photo Film Co., Ltd. Matériau sensible à la lumière, en couleur développable à la chaleur
EP0754969A2 (fr) * 1995-07-18 1997-01-22 Agfa-Gevaert N.V. Procédé pour produire une suspension aqueuse de particules contenant un sel d'argent d'un acide organique carboxylique substantiellement insensible à la lumière pour la production de matériaux (photo)thermographiques

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3615533A (en) * 1968-03-11 1971-10-26 Eastman Kodak Co Heat and light sensitive layers containing hydrazones
EP0715209A2 (fr) * 1994-11-25 1996-06-05 Fuji Photo Film Co., Ltd. Matériau sensible à la lumière, en couleur développable à la chaleur
EP0754969A2 (fr) * 1995-07-18 1997-01-22 Agfa-Gevaert N.V. Procédé pour produire une suspension aqueuse de particules contenant un sel d'argent d'un acide organique carboxylique substantiellement insensible à la lumière pour la production de matériaux (photo)thermographiques

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