EP0903627B1 - Haftvermittlungsschichten für die Verwendung in thermographischen Materialien - Google Patents

Haftvermittlungsschichten für die Verwendung in thermographischen Materialien Download PDF

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Publication number
EP0903627B1
EP0903627B1 EP98202644A EP98202644A EP0903627B1 EP 0903627 B1 EP0903627 B1 EP 0903627B1 EP 98202644 A EP98202644 A EP 98202644A EP 98202644 A EP98202644 A EP 98202644A EP 0903627 B1 EP0903627 B1 EP 0903627B1
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EP
European Patent Office
Prior art keywords
subbing layer
substantially light
insensitive
thermographic material
acid
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EP98202644A
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English (en)
French (fr)
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EP0903627A1 (de
Inventor
Carlo Uyttendaele
Ingrid Geuens
Ivan Hoogmartens
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Agfa Gevaert NV
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Agfa Gevaert NV
Agfa Gevaert AG
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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
    • G03C1/4989—Photothermographic systems, e.g. dry silver characterised by a thermal imaging step, with or without exposure to light, e.g. with a thermal head, using a laser
    • 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
    • G03C1/49872—Aspects relating to non-photosensitive layers, e.g. intermediate protective layers
    • 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
    • G03C1/76—Photosensitive materials characterised by the base or auxiliary layers
    • G03C1/91—Photosensitive materials characterised by the base or auxiliary layers characterised by subbing layers or subbing means
    • 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
    • G03C1/76—Photosensitive materials characterised by the base or auxiliary layers
    • G03C1/91—Photosensitive materials characterised by the base or auxiliary layers characterised by subbing layers or subbing means
    • G03C1/93—Macromolecular substances therefor

Definitions

  • the present invention relates to a substantially light-insensitive thermographic material comprising a subbing layer with a low concentration of leachable non-fluoro-halide ions.
  • Thermal imaging or thermography is a recording process wherein images are generated by the use of thermal energy.
  • thermography three approaches are known:
  • thermographic materials are of the chemical type. On heating to a certain conversion temperature, an irreversible chemical reaction takes place and a coloured image is produced.
  • a wide variety of chemical systems has been suggested some examples of which have been given on page 138 of "Imaging Systems” by Kurt I. Jacobson-Ralph E. Jacobson, The Focal Press - London and New York (1976), describing the production of a silver metal image by means of a thermally induced oxidation-reduction reaction of a silver soap with a reducing agent.
  • JP 57-69,095 discloses a support coated with a subbing layer containing an ionomer, and then coated with a heat-sensitive recording layer whose solubility in water decreases upon heating to give a thermographic sheet.
  • EP-A 496 017 discloses a heat-sensitive recording medium, comprising: (a) a synthetic-resin support; (b) an ionomer-resin layer on said support; and (c) a heat-sensitive recording layer on said ionomer resin layer.
  • thermosensitive recording sheet comprising: a support material; a primer layer formed on the support material and comprising a filler and a binder agent; a thermosensitive colouring layer formed on the primer layer and comprising a colourless light-coloured leuco dye, and an acidic material which colours the leuco dye upon application of heat hereto; and a protective layer formed on the thermosensitive colouring layer and comprising a water-soluble agent and a filler.
  • thermographic materials coated from aqueous media were surprisingly, considering their thinness relative to the thickness of the thermosensitive element thereof, dependent upon the choice of subbing layer and that, moreover, polymer subbing layers used to promote adhesion between polyester support and conventional photographic emulsion layers were in the main unusable (see COMPARATIVE EXAMPLE 2) due to prohibitive light-sensitivity and poor archivability.
  • subbing layers for use on the supports of thermographic materials, which have no adverse effect upon the light-stability and archivability of thermographic materials.
  • thermographic materials coatable from aqueous media which exhibit improved archivability and/or improved light stability, while maintaining high maximum density and low minimum density levels upon printing.
  • thermosensitive element has a considerable influence on the light-stability and archivability of a substantially light-insensitive black and white thermographic material despite the thinness of a subbing layer compared to that of the thermosensitive element.
  • certain ingredients such as silica, whether colloidal or non-colloidal, have, above a concentration of 20% by weight, and the presence of non-fluoro-halide ions leachable into water at a concentration of 0.6mg/m 2 or more have been found to have a prohibitive effect on the light-stability and archivability of thermographic materials coated from aqueous media.
  • thermographic material comprising a polymeric or polymer-coated support, a subbing layer on the support and on the same side of the support as the subbing layer a thermosensitive element containing a substantially light-insensitive organic silver salt, a reducing agent therefor in thermal working relationship therewith and a binder, characterized in that the subbing layer contains a binder, less than 20% by weight of silica and covalently bonded acid groups in said binder, if present, are either substantially present as free acid or substantially present as acid salts and has a leachable non-fluoro-halide ion content into water at room temperature over a period of 120 minutes of less than 0.6mg/m 2 .
  • a process for producing the above-referred to substantially light-insensitive thermographic material comprising the steps of: coating the support with a subbing-layer composition thereby forming the subbing layer; producing one or more aqueous coating compositions together containing the substantially light-insensitive organic silver salt, the reducing agent and the binder; and applying the one or more aqueous coating compositions to the same side of the support as the subbing layer thereby forming after drying the thermosensitive element.
  • the subbing layer used in accordance with the present invention contains a binder, less than 20% by weight of silica and covalently bonded acid groups in the binder, if present, are either substantially present as free acid or substantially present as acid salts and the leachable non-fluoro-halide ion content into water at room temperature of the subbing layer is less than 0.6mg/m 2 over a period of 120 minutes.
  • the subbing layer used in accordance with the present invention may consist of one or more sub-layers.
  • the leachable non-fluoro-halide ion is preferably a chloride ion.
  • ionic group an ionized group, for example carboxylate, sulfinate, sulfonate, quaternary ammonium, quaternary phosphonium, ternary sulfonium and phosphate groups.
  • Suitable binders include any natural, modified natural or synthetic resins, polysilicic acid, hydrolyzed polyalkoxysilanes etc. or mixtures thereof.
  • the preferred leachable non-fluoro-halide ion content of the subbing layer used in accordance with the present invention is less than 0.5mg/m 2 , with less than 0.4mg/m 2 being particularly preferred.
  • Preferred ingredients for the subbing layer used in accordance with the present invention are a polymer latex, polyethylene wax and hydrolyzed polyalkoxysilanes.
  • polyalkoxysilane is meant a silane with a least two hydrolyzable alkoxy-groups.
  • Particularly preferred polymer latexes for use in the subbing layer of the present invention are producible with monomers selected from the group consisting of acrylates, methacrylates, vinyl esters, acrylic acid, methacrylic acid, itaconic acid, vinylidene chloride, polyisocyanates, aromatic polycarboxylic acids and polyols.
  • Suitable ingredients for use in the subbing layer in accordance with the present invention are:
  • aqueous for the purposes of the present invention includes mixtures of water with 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 pyrrolidone; 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 pyrrolidone
  • methoxypropanol and ketones e.g. 2-propanone and 2-butanone etc.
  • substantially light-insensitive is meant not intentionally light sensitive.
  • substantially solvent-free aqueous medium is meant that solvent, if present, is present in amounts below 10% by volume of the aqueous medium.
  • thermographic material comprising a thermosensitive element including a substantially light-insensitive organic silver salt, an organic reducing agent therefor in thermal working relationship therewith and a binder.
  • the element may comprise a layer system in which the ingredients may be dispersed in different layers, with the proviso that the substantially light-insensitive organic silver salt and the organic reducing agent are in thermal working relationship with one another i.e. during the thermal development process the reducing agent must be present in such a way that it is able to diffuse to the substantially light-insensitive organic silver salt particles so that reduction of the organic silver salt can take place.
  • Preferred substantially light-insensitive organic silver salts used in the thermographic materials are silver salts of aliphatic carboxylic acids known as fatty acids, wherein the aliphatic carbon chain has preferably at least 12 C-atoms, e.g. silver laurate, silver palmitate, silver stearate, silver hydroxystearate, silver oleate and silver behenate, which silver salts are also called "silver soaps".
  • Silver salts of modified aliphatic carboxylic acids with thioether group as described e.g. in GB-P 1,111,492 and other organic silver salts as described in GB-P 1,439,478, e.g. silver benzoate may likewise be used to produce a thermally developable silver image. Combinations of different organic silver salts may also be used in the thermographic materials of the present invention.
  • a process for producing a suspension of particles containing a substantially light-insensitive organic silver salt is disclosed in EP-A 754 969.
  • Suitable organic reducing agents for use in the thermographic materials of the present invention for the reduction of the substantially light-insensitive organic silver salt are organic compounds containing at least one active hydrogen atom linked to O, N or C, such as is the case with: catechol; hydroquinone; aminophenols; METOLTM; p-phenylenediamines; alkoxynaphthols, e.g. 4-methoxy-1-naphthol described in US-P 3,094,417; 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-P 4,082,901; hydrazine derivatives; and reductones e.g. ascorbic acid; see also US-P 3,074,809, 3,080,254, 3,094,417 and 3,887,378.
  • auxiliary reducing agents are e.g. sterically hindered phenols, such as described in US-P 4,001,026; bisphenols, e.g.
  • stannous stearate described in US-P 3,460,946 and 3,547,648 or organic reducing metal salts, e.g. stannous stearate described in US-P 3,460,946 and 3,547,648.
  • the auxiliary reducing agents may be present in the imaging layer or in a polymeric binder layer in thermal working relationship thereto.
  • thermosensitive element of the thermographic materials of the present invention may be coated onto a support in sheet- or web-form from an organic solvent containing the binder dissolved therein or may be applied from an aqueous medium using water-soluble or water-dispersible binders.
  • Suitable binders for coating from an organic solvent are all kinds of natural, modified natural or synthetic resins or mixtures of such resins, wherein the organic heavy metal salt can be dispersed homogeneously: e.g. cellulose derivatives, cellulose esters, carboxymethylcellulose, starch ethers, galactomannan, polyurethanes, polyesters, polymers derived from ⁇ , ⁇ -ethylenically unsaturated compounds such as after-chlorinated polyvinyl chloride, partially hydrolyzed polyvinyl acetate, polyvinyl alcohol, polyvinyl acetals preferably polyvinyl butyral and homopolymers and copolymers produced using monomers selected from the group consisting of: vinyl chloride, vinylidene chloride, vinyl esters, acrylonitrile, acrylamides, methacrylamides. methacrylates, acrylates, methacrylic acids, acrylic acids, vinyl esters, styrenes and alkenes; or mixtures thereof.
  • Suitable water-soluble film-forming binders are: polyvinyl alcohol, polyacrylamide, 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 polymer. It should be noted that there is no clear cut transition between a polymer dispersion and a polymer solution in the case of very small polymer particles resulting in the smallest particles of the polymer being dissolved and those slightly larger being in dispersion.
  • Preferred water-dispersible binders for use according to the present invention are water-dispersible film-forming polymer with covalently bonded ionic groups selected from the group consisting of sulfonate, sulfinate, carboxylate, phosphate, quaternary ammonium, tertiary sulfonium and quaternary phosphonium groups. Water-dispersible binders with crosslinkable groups, e.g. epoxy groups, aceto-acetoxy groups and crosslinkable double bonds are also preferred.
  • polymer latexes are polymer latexes.
  • the binder to organic silver salt weight ratio is preferably in the range of 0.2 to 6, and the thickness of the recording layer is preferably in the range of 1 to 50 ⁇ m.
  • 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.
  • thermographic materials according to the present invention may contain one or more toning agents.
  • the toning agents should be in thermal working relationship with the substantially light-insensitive organic silver salt and reducing agents during thermal processing. Any known toning agent from thermography or photothermography may be used. Suitable toning agents are the phthalimides and phthalazinones within the scope of the general formulae described in US-P 4,082,901 and the toning agents described in US-P 3,074,809, US-P 3,446,648 and US-P 3,844,797.
  • Particularly useful toning agents are the heterocyclic toner compounds of the benzoxazine dione or naphthoxazine dione type described in GB-P 1,439,478, US-P 3,951,660 and US-P 5,599,647.
  • thermographic materials of the present invention may further contain one or more surfactants.
  • surfactants may be anionic, non-ionic or cationic surfactants. Examples of suitable surfactants are:
  • thermographic materials according to the present invention may also contain dispersants.
  • Suitable dispersants are: natural polymeric substances, a synthetic polymeric substances and finely divided powders, e.g. silica.
  • stabilizers and antifoggants may be incorporated into the thermographic materials of the present invention.
  • thermographic material may contain other additives such as free fatty acids, surface-active agents, antistatic agents, e.g. non-ionic antistatic agents including a fluorocarbon group as e.g. in F 3 C(CF 2 ) 6 CONH(CH 2 CH 2 O)-H, silicone oil, ultraviolet light absorbing compounds, white light reflecting and/or ultraviolet radiation reflecting pigments, silica, and/or optical brightening agents.
  • antistatic agents e.g. non-ionic antistatic agents including a fluorocarbon group as e.g. in F 3 C(CF 2 ) 6 CONH(CH 2 CH 2 O)-H
  • silicone oil e.g. in F 3 C(CF 2 ) 6 CONH(CH 2 CH 2 O)-H
  • ultraviolet light absorbing compounds e.g. in F 3 C(CF 2 ) 6 CONH(CH 2 CH 2 O)-H
  • silicone oil e.g. in F 3 C(CF 2 ) 6 CONH(CH 2 CH 2 O)-H
  • the support for the thermographic material according to the present invention is polymer or polymer-coated and may be transparent, translucent or opaque and is preferably a thin flexible carrier made e.g. from 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 made of an opacified resin composition.
  • thermo-sensitive element may also be provided for the thermo-sensitive element. In general this protects the thermosensitive element from atmospheric humidity and from surface damage by scratching etc. and prevents direct contact of printheads or heat sources with said recording layers. Protective layers for thermosensitive elements which come into contact with and have to be transported past a heat source under pressure, have to exhibit resistance to local deformation and good slipping characteristics during transport past the heat source during heating.
  • a slipping layer being said outermost layer, may comprise a dissolved lubricating material and/or particulate material, e.g. talc particles, optionally protruding from the outermost layer.
  • suitable lubricating materials are a surface active agent, a liquid lubricant, a solid lubricant or mixtures thereof, with or without a polymeric binder.
  • Suitable slipping layer compositions are described, for example, in EP 138 483, EP 227 090, US-P 4,567,113, US-P 4,572,860, US-P 4,717,711, EP-A 311 841, US 5,587,350, US 5,536,696, US 5,547,914, WO 95/12495, EP-A 775 592 and EP-A 775 595.
  • thermographic 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
  • Thermographic imaging is carried out by the image-wise application of heat either in analogue fashion by direct exposure through an image of by reflection from an image, or in digital fashion pixel by pixel either by using an infra-red heat source, for example with a Nd-YAG laser or other infra-red laser, or by direct thermal imaging with a thermal head.
  • thermal printing image signals are converted into electric pulses and then through a driver circuit selectively transferred to a thermal printhead.
  • the thermal printhead consists of microscopic heat resistor elements, which convert the electrical energy into heat via Joule effect.
  • the electric pulses thus converted into thermal signals manifest themselves as heat transferred to the surface of the thermal paper wherein the chemical reaction resulting in colour development takes place.
  • Such thermal printing heads may be used in contact or close proximity with the recording layer.
  • the operating temperature of common thermal printheads is in the range of 300 to 400°C and the heating time per picture element (pixel) may be less than 1.0 ms, the pressure contact of the thermal printhead with the recording material being e.g. 200-500g/cm 2 to ensure a good transfer of heat.
  • the image-wise heating of the recording layer with said thermal printing heads may proceed through a contacting but removable resin sheet or web wherefrom during said heating no transfer of recording material can take place.
  • the image signals for modulating the laser beam or current in the micro-resistors of a thermal printhead are obtained directly e.g. from opto-electronic scanning devices or from an intermediary storage means, e.g. magnetic disc or tape or optical disc storage medium, optionally linked to a digital image work station wherein the image information can be processed to satisfy particular needs.
  • an intermediary storage means e.g. magnetic disc or tape or optical disc storage medium
  • thermographic material can be not suitable for reproducing images with fairly large number of grey levels as is required for continuous tone reproduction.
  • EP-A 622 217 discloses a method for making an image using a direct thermal imaging element producing improvements in continuous tone reproduction. Image-wise heating of the thermographic material can also be carried out using an electrically resistive ribbon incorporated into said material. Image- or pattern-wise heating of the thermographic material may also proceed by means of pixel-wise modulated ultra-sound, using e.g. an ultrasonic pixel printer as described e.g. in US-P 4,908,631.
  • Thermographic 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, and reflection type prints, for example in the hard copy field.
  • 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.
  • a 0.34mm thick polyethylene terephthalate sheet was first coated to a wet thickness of 7 ⁇ m with a composition which after drying and longitudinal and transverse stretching produced a 175 ⁇ m thick support coated with a sub-layer with the following composition, expressed as the coating weights of the ingredients present:
  • the 175 ⁇ m thick longitudinally stretched polyethylene terephthalate support was then coated on one side with a composition which after drying at 130°C produced a second sub-layer with the following layer composition, expressed as the coating weights of the ingredients present:
  • a 0.34mm thick polyethylene terephthalate sheet was first coated to a wet thickness of 7 ⁇ m with a composition which after drying and longitudinal and transverse stretching produced a 175 ⁇ m thick support coated with a sub-layer with the following composition, expressed as the coating weights of the ingredients present:
  • the 175 ⁇ m thick longitudinally stretched polyethylene terephthalate support was then coated on one side with a composition which after drying at 130°C produced a second sub-layer with the following layer composition, expressed as the coating weights of the ingredients present:
  • a 0.34mm thick polyethylene terephthalate sheet was coated to a thickness of 0.1mm with a composition which after drying and longitudinal and transverse stretching produced a 175 ⁇ m thick support coated with the following subbing-layer composition of SUBBING LAYER NUMBER C2 expressed as the coating weights of the ingredients present:
  • a 0.34mm thick polyethylene terephthalate sheet was coated to a thickness of 0.1mm with a composition which after drying and longitudinal and transverse stretching produced a 175 ⁇ m thick support coated on with the following subbing-layer composition of subbing layer number 01 expressed as the coating weights of the ingredients present:
  • a 0.34mm thick polyethylene terephthalate sheet was coated to a thickness of 7 ⁇ m with a composition which after drying and longitudinal and transverse stretching produced a 175 ⁇ m thick support coated with the following subbing-layer composition of subbing layer number 02 expressed as the coating weights of the ingredients present:
  • the chloride-ion content leachable during overcoating with an aqueous dispersion or solution was simulated by placing a 10 x 5cm 2 piece of subbing layer-coated polyethylene terephthalate in 25mL of deionized water for a period of 2 hours and determining the quantity of chloride ions leached out by injecting samples of the leaching water directly into a DIONEX QIK ANALYSER ion chromatograph The detection limit with these measurements was limited to 0.1ppm by the deionized water used in the leaching experiments, which had a chloride ion concentration of 0.02 to 0.06 ppm. The results obtained are given below in table 1:
  • Wavelength dispersive X-ray fluorescence (WDXRF) measurements were carried out on some of the supports to obtain a qualitative estimate of the total chlorine constant of the supports i.e. both covalently bound chlorine and chloride ions. These showed no detectable chlorine in an uncoated support, a very small quantity in subbing layer number 01 and a small quantity in subbing layer C3.
  • WDXRF Wavelength dispersive X-ray fluorescence
  • a gelatin solution was produced by adding 660g of K7598 to 2319g of deionized water, allowing the gelatin to swell for 30 minutes and heating the mixture to 50°C. The gelatin solution was then added to the aqueous silver behenate dispersion with vigorous stirring with a DISSOLVERTM, after which the stirring was continued for a further 15 minutes producing a gelatinous aqueous dispersion of silver behenate containing: 14.3% of silver behenate, 1.07% of Surfactant Nr. 5 and 6.28% of gelatin.
  • the tone modifier dispersion was prepared by first dissolving 8.8g of K7598 in 71.4g of deionized water by first adding the gelatin, then allowing the gelatin to swell for 30 minutes and finally heating to 50°C. 20 g of T01 was added with ULTRA-TURRAXTM stirring to this gelatin solution at 50°C, and the stirring continued for a further 5 minutes. Finally the resulting dispersion was pumped through a DYNOMILLTM for 2 hours to produce the final tone modifier dispersion containing: 20% of T01 and 8.8% of gelatin.
  • thermosensitive element Preparation of the thermosensitive element
  • the coating dispersion was prepared by adding 324g of the gelatinous aqueous dispersion of silver behenate to 165.7g of deionized water, heating the dispersion to 36°C, then adding 81g of the tone modifier dispersion as flakes, followed by stirring for 15 minutes before adding with stirring 70.8g of a 30% latex dispersion of polymer latex number 1 at pH 5, a further 5 minutes stirring was followed by the addition with stirring of 103.24g of a 7.25% aqueous solution of boric acid at 50°C, 11.01g of R01 in 20.52g of ethanol and 15.7g of a 3.7% aqueous solution of formaldehyde to produce a dispersion containing: 5.85% of silver behenate, 0.44% of Surfactant nr 5, 3.47% of gelatin, 2.68% of polymer latex number 1, 1.39% of R01, 0.94% of boric acid, 2.05% of T01 and 0.07% of formaldehyde.
  • the resulting emulsion was then doctor blade-coated to a wet thickness of 60 ⁇ m with the blade at a setting of 100 ⁇ m onto an unsubbed 100 ⁇ m thick polyethylene terephthalate support in the case of COMPARATIVE EXAMPLE 1 and a 175 ⁇ m thick polyethylene terephthalate supports coated with different subbing layers in the cases of COMPARATIVE EXAMPLE 2 & 3and INVENTION EXAMPLES 1 & 2 and dried for 10 minutes at 50°C, producing a silver behenate coverage of 3.8g/m 2 .
  • thermosensitive element The adhesion of the thermosensitive element to the polyethylene terephthalate support was evaluated for the thermographic materials of COMPARATIVE EXAMPLES 1 to 3 and INVENTION EXAMPLES 1 & 2 using a tape test.
  • a 10 x 10 cm 2 sample was prepared and laid flat on a table and a section of TESAPACKTM 4122 tape, available from BEIERSDORF AG, Hamburg, Germany, was placed across the width of the sample and smoothed out by hand to ensure uniform adhesion.
  • TESAPACKTM 4122 tape available from BEIERSDORF AG, Hamburg, Germany
  • the print head was separated from the imaging layer by a thin intermediate material contacted with a slipping layer of a separable 5 ⁇ m thick polyethylene terephthalate ribbon coated successively with a subbing layer, heat-resistant layer and the slipping layer (anti-friction layer) giving a ribbon with a total thickness of 6 ⁇ m.
  • the printer was equipped with a thin film thermal head with a resolution of 300 dpi and was operated with a line time of 19ms (the line time being the time needed for printing one line). During this line time the print head received constant power.
  • the average printing power being the total amount of electrical input energy during one line time divided by the line time and by the surface area of the heat-generating resistors was 1.6 mJ/dot being sufficient to obtain maximum optical density in each of the thermographic materials of COMPARATIVE EXAMPLES 1 to 3 and INVENTION EXAMPLES 1 & 2.
  • the stability of the image background of the prints made with the thermographic materials of COMPARATIVE EXAMPLES 1 to 3 and INVENTION EXAMPLES 1 & 2 was evaluated on the basis of the change in minimum (background) density measured through a blue filter using a MACBETHTM TR924 densitometer upon exposure on top of the white PVC window of a specially constructed light-box placed for 3 days in a V ⁇ TSCH conditioning cupboard set at 30°C and a relative humidity (RH) of 85%. Only a central area of the window 550mm long by 500mm wide was used for mounting the test materials to ensure uniform exposure.
  • the stainless steel light-box used was 650mm long, 600mm wide and 120mm high with an opening 610mm long and 560mm wide with a rim 10mm wide and 5mm deep round the opening, thereby forming a platform for a 5mm thick plate of white PVC 630mm long and 580mm wide, making the white PVC-plate flush with the top of the light-box and preventing light loss from the light-box other than through the white PVC-plate.
  • This light-box was fitted with 9 PLANILUXTM TLD 36W/54 fluorescent lamps 27mm in diameter mounted length-wise equidistantly from the two sides, with the lamps positioned equidistantly to one another and the sides over the whole width of the light-box and with the tops of the fluorescent tubes 30mm below the bottom of the white PVC plate and 35mm below the materials being tested.
  • Table 3 The results are summarized in table 3.
  • thermographic recording material of COMPARATIVE EXAMPLE 2 with subbing layer number C1 with 1.95mg/m 2 of leachable chloride ions and less marked with the thermographic recording material of COMPARATIVE EXAMPLE 3 with subbing layer number C3 with 0.65mg/m 2 of leachable chloride ions, due to the poorish light stability of the thermosensitive element itself, which largely masked any slight differences in the influence of the subbing layers upon the light stability of the thermographic recording material as a whole, as shown by the small differences in ⁇ D min (blue) after the light box test between the thermographic recording materials of COMPARATIVE EXAMPLE 3 with a subbing layer falling outside that used in the thermographic recording material of the present invention and INVENTION EXAMPLES 1 and 2 with subbing layer number 01 and 02 with 0.3mg/m 2 and ⁇ 0.5mg/m 2 of leachable chloride ions respectively used in the thermographic recording materials according to the present invention.
  • the silver behenate dispersion was produced as follows: dispersing 25kg (73.5M) behenic acid was dispersed with stirring at at 80°C in 1g of a 10% solution of Surfactant Nr 5/g behenic acid made up to 250L with deionized water at a temperature of 80°C; then 36.75L of a 2M aqueous solution of sodium hydroxide was added over a period of 10 to 20 minutes to give a clear solution substantially containing sodium behenate; then 25L of a 2.94M aqueous solution of silver nitrate was added with stirring at a rate of 0.163moles/moles silver behenate min to convert the sodium behenate completely into silver behenate; and finally ultrafiltration was carried out with a 500000 MW polysulfone cartridge filter at room temperature to concentrate the resulting silver behenate dispersion, the final AgB-concentration was 16.7% with 0.07g of Surfactant Nr 5/g AgB, the residual conductivity was 1.0mS/cm
  • thermosensitive element Preparation of the thermosensitive element
  • thermosensitive element containing:
  • thermographic recording material of INVENTION EXAMPLE 3 using subbing layer number 01 with a leachable chloride content of 0.3mg/m 2 exhibited a significantly lower sensitivity to light, reduced ⁇ D min -values, compared with the thermographic recording material of COMPARATIVE EXAMPLE 4 using subbing layer number C3 with a leachable chloride content of 0.65 mg/m 2 outside the chloride content of the subbing layers used in the thermographic recording material according to the present invention.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
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  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Heat Sensitive Colour Forming Recording (AREA)

Claims (10)

  1. Ein wesentlich lichtunempfindliches thermografisches Schwarzweißmaterial mit einem polymeren oder polymerbeschichteten Träger, einer Haftschicht auf dem Träger und an der gleichen Seite des Trägers wie die Haftschicht einem wärmeempfindlichen Element, das ein wesentlich lichtunempfindliches organisches Silbersalz, ein Reduktionsmittel dafür in thermischer wirksamer Beziehung dazu und ein Bindemittel enthält, dadurch gekennzeichnet, daß die Haftschicht ein Bindemittel und weniger als 20 Gew.-% Kieselsäure enthält, eventuelle kovalent gebundene Säuregruppen im Bindemittel entweder im wesentlichen als freie Säuren oder im wesentlichen als Säuresalze enthalten sind und der Gehalt an bei Zimmertemperatur über einen Zeitraum von 120 Minuten in Wasser auslaugbaren Ionen außer Fluorhalogenidionen in der Haftschicht weniger als 0,6 mg/m2 beträgt.
  2. Wesentlich lichtunempfindliches thermografisches Material nach Anspruch 1, dadurch gekennzeichnet, daß der Gehalt an auslaugbaren Ionen außer Fluorhalogenidionen in der Haftschicht weniger als 0,5 mg/m2 beträgt.
  3. Wesentlich lichtunempfindliches thermografisches Material nach Anspruch 1, dadurch gekennzeichnet, daß das Ion, das kein Fluorhalogenidion ist, ein Chloridion ist.
  4. Wesentlich lichtunempfindliches thermografisches Material nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß die Haftschicht einen polymeren Latex enthält.
  5. Wesentlich lichtunempfindliches thermografisches Material nach Anspruch 4, dadurch gekennzeichnet, daß der polymere Latex mit Monomeren aus der Gruppe bestehend aus Acrylaten, Methacrylaten, Vinylestern, Acrylsäure, Methacrylsäure, Itakonsäure, Vinylidenchlorid, Polyisocyanaten, aromatischen Polycarbonsäuren und Polyolen hergestellt werden kann.
  6. Wesentlich lichtunempfindliches thermografisches Material nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß die Haftschicht ein hydrolysiertes Polyalkoxysilan enthält.
  7. Wesentlich lichtunempfindliches thermografisches Material nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß die Haftschicht Polyethylenwachs enthält.
  8. Wesentlich lichtunempfindliches thermografisches Material nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß das wärmeempfindliche Element mit einer Schutzschicht überzogen ist.
  9. Wesentlich lichtunempfindliches thermografisches Material nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß das wesentlich lichtunempfindliche organische Silbersalz ein Silbersalz einer organischen Carbonsäure ist.
  10. Ein durch die nachstehenden Schritte gekennzeichnetes Verfahren zur Herstellung eines wesentlich lichtunempfindlichen thermografischen Materials nach einem der vorstehenden Ansprüche : Beschichtung des Trägers mit einer Haftschichtzusammensetzung zur Bildung der Haftschicht, Anfertigung einer oder mehrerer wäßriger Gießzusammensetzungen, die das wesentlich lichtunempfindliche organische Silbersalz, das Reduktionsmittel und das Bindemittel enthalten, und Auftrag der einen oder mehreren wäßrigen Gießzusammensetzungen auf die gleiche Seite des Trägers wie die Haftschicht, wobei nach Trocknung das wärmeempfindliche Element erhalten wird.
EP98202644A 1997-09-17 1998-08-06 Haftvermittlungsschichten für die Verwendung in thermographischen Materialien Expired - Lifetime EP0903627B1 (de)

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US6207364B1 (en) 1998-04-21 2001-03-27 Konica Corporation Thermally developable material
JP3973798B2 (ja) 1999-06-25 2007-09-12 富士フイルム株式会社 非感光性脂肪酸銀塩粒子の調製方法
US6713241B2 (en) 2002-08-09 2004-03-30 Eastman Kodak Company Thermally developable emulsions and imaging materials containing binder mixture

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JPH08278590A (ja) * 1995-04-05 1996-10-22 Fuji Photo Film Co Ltd 記録材料及びその製造方法
EP0779539B1 (de) * 1995-11-27 2002-07-17 Agfa-Gevaert Thermographisches Material mit einer organischen antistatischen Aussenschicht

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