EP0903625A1 - Neue Reduktionsmittel zur Verwendung in thermographischen Aufzeichnungsmaterialien - Google Patents

Neue Reduktionsmittel zur Verwendung in thermographischen Aufzeichnungsmaterialien Download PDF

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Publication number
EP0903625A1
EP0903625A1 EP98202551A EP98202551A EP0903625A1 EP 0903625 A1 EP0903625 A1 EP 0903625A1 EP 98202551 A EP98202551 A EP 98202551A EP 98202551 A EP98202551 A EP 98202551A EP 0903625 A1 EP0903625 A1 EP 0903625A1
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EP
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Prior art keywords
substituted
alkyl
aryl
dihydroxyphenyl
substantially light
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EP98202551A
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English (en)
French (fr)
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EP0903625B1 (de
Inventor
David Terrell
Johan Loccufier
Geert Defieuw
Ivan Hoogmartens
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Agfa Gevaert NV
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Agfa Gevaert NV
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/494—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
    • G03C1/49827—Reducing agents
    • 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
    • G03C2200/00—Details
    • G03C2200/45—Polyhydroxybenzene

Definitions

  • the present invention relates to black and white substantially light-insensitive thermographic recording materials comprising a thermosensitive element containing a substantially light-insensitive organic silver salt and a novel reducing agent.
  • thermography is a recording process wherein images are generated by the use of thermal energy.
  • thermography three approaches are known:
  • thermoplastic binder e.g ethyl cellulose
  • water-insoluble silver salt e.g. silver stearate
  • organic reducing agent of which 4-methoxy-1-hydroxy-dihydronaphthalene is a representative.
  • EP-A 248 405 discloses a thermal recording material with a colour-developing layer, which contains an electron acceptor and an electron donor in addition to the usual additives, characterized in that the electron acceptor is a metallic double salt of a long-chain fatty acid with 16 to 35 carbon atoms.
  • EP-A 599 580 discloses a thermal recording sheet comprising , in order: (a) a substrate; (b) an intermediate layer which comprises a pigment having an oil absorption according to Japanese Industrial Standard (JIS) K501 of 100mL/100g or less; and (c) a thermal color developing layer which comprises a leuco dye type chromogenic component consisting of a leuco dye and an organic color developer and a metal chelate type chromogenic component consisting of an electron acceptor and an electron donor, wherein: the organic color developer is at least one of compounds of formula (I) and formula (II): wherein R is propyl, isopropyl, or butyl; the electron acceptor is a metal double salt of a fatty acid having 16 to 35 carbon atoms; and the electron donor is a polyhydric aromatic compound of formula (III): wherein R is a C 18 - to C 35 -alkyl group, wherein R 1 is a C 18 - to C 35 -alkyl
  • US-P 5,582,953 discloses a direct recording process wherein a direct thermal recording material is heated dot-wise and the direct thermal recording material comprises on a substrate an imaging layer, the imaging layer containing uniformly distributed in a film-forming polymeric binder (i) one or more substantially light-insensitive organic silver salts being no double salts, the silver salt(s) being in thermal working relationship with (ii) an organic reducing agent therefor, wherein the reducing agent is a benzene compound the benzene nucleus of which is substituted with a substituent linked to the benzene nucleus by means of a carbonyl group, wherein the carbonyl group is linked to the benzene nucleus at a position which is designated the 1-position of the benzene nucleus, wherein the benzene nucleus is further substituted in a 3-position relative to the 1-position with a single hydroxy group and in a 4-position relative to the 1-position with a single hydroxy group, wherein the reducing agent is
  • thermographic recording materials whose prints have high D max and low D min levels and exhibit improved archivability and/or improved light stability and/or improved colour neutrality over the whole range of print densities.
  • thermographic recording materials coated from both aqueous and solvent media containing novel 3,4-dihydroxyphenyl compounds exhibit substantially improved archivability over the whole density range, substantially improved light stability and improved colour neutrality over prints made with thermographic recording materials containing a reducing agent according to the teaching of US-P 5,582,953
  • a process for producing a substantially light-insensitive black and white monosheet thermographic recording material is also provided by the present invention comprising the steps of: producing one or more aqueous coating compositions containing together 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.
  • 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 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 etc
  • glycols e.g. ethylene glycol
  • glycerine glycerine
  • N-methyl pyrrolidone methoxypropanol
  • 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.
  • the organic reducing agent used in the present invention is a 1,2-dihydroxyphenyl-compound represented by formula (I).
  • formula (I) represents an acid
  • salts of the acid are also included under formula (I).
  • Preferred reducing agents for use in the present invention are selected from the group consisting of: consisting of: aryl(3,4-dihydroxyphenyl)sulfinates, alkyl(3,4-dihydroxyphenyl)sulfinates, 3,4-dihydroxyphenyl-alkylsulfones, 3,4-dihydroxyphenyl-arylsulfones, aryl(3,4-dihydroxyphenyl)sulfonates, alkyl(3,4-dihydroxyphenyl)sulfonates and 3,4-dihydroxybenzonitrile compounds.
  • Suitable 1,2-dihydroxyphenyl-compounds for use according to the present invention are:
  • thermographic recording 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 thermosensitive 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 1,2-dihydroxyphenyl-compound are in thermal working relationship with one another i.e. during the thermal development process the 1,2-dihydroxyphenyl-compound 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 substantially light-insensitive organic silver salt can take place.
  • Preferred substantially light-insensitive organic silver salts for use in the thermographic recording 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".
  • thermographic recording materials of the present invention A preferred process for producing a suspension of particles containing a substantially light-insensitive organic silver salt is disclosed in EP-A 754 969.
  • auxiliary reducing agents are e.g. hydroquinone or catechol substituted with strongly electron-withdrawing groups such as sulfonic acid groups; sterically hindered phenols, such as described in US-P 4,001,026; bisphenols, e.g.
  • thermographic recording material comprises a support and a thermosensitive element which further contains a catechol compound substituted with a strongly electron-withdrawing group.
  • thermosensitive element of the thermographic recording 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, polycarbonates, 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 acid, acrylic acid, vinyl esters, styrenes, dienes and alken
  • 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 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 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 for use according the the present invention 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.
  • polymer latexes suitable for use in the present invention are polymer latexes.
  • Compositions of polymer latexes suitable for use in the present invention are given in the table below: polymer latex nr.
  • 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.
  • heat solvent in this invention is meant a non-hydrolyzable organic material which is in a solid state in the recording layer at temperatures below 50°C, but becomes a plasticizer for the recording layer where thermally heated and/or a liquid solvent for at least one of the redox-reactants.
  • thermographic recording materials 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 heterocyclic compounds of the benzoxazine dione or naphthoxazine dione type disclosed in GB-P 1,439,478, US-P 3,951,660 and US-P 5,599,647.
  • the thermosensitive element further contains at least one polycarboxylic acid and/or anhydride thereof in a molar percentage of at least 15 with respect to the, substantially light-insensitive organic silver salt and in thermal working relationship therewith.
  • the polycarboxylic acid may be aliphatic (saturated as well as unsaturated aliphatic and also cycloaliphatic) as disclosed in US-P 5,527,758 or an aromatic polycarboxylic acid, may be substituted and may be used in anhydride form or partially esterified on the condition that at least two free carboxylic acids remain or are available in the heat recording step.
  • thermographic recording materials of the present invention In order to obtain improved shelf-life and reduced fogging, stabilizers and antifoggants may be incorporated into the thermographic recording materials of the present invention.
  • thermographic recording materials of the present invention may contain one or more surfactants, which may be anionic, non-ionic or cationic surfactants and/or one or more dispersants.
  • surfactants are:
  • Suitable dispersants are natural polymeric substances, synthetic polymeric substances and finely divided powders, for example finely divided non-metallic inorganic powders such as silica.
  • thermographic recording material may contain other additives such as free fatty acids, antistatic agents, e.g. non-ionic antistatic agents including a fluorocarbon group e.g. 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 e.g. F 3 C(CF 2 ) 6 CONH(CH 2 CH 2 O)-H
  • silicone oil e.g. F 3 C(CF 2 ) 6 CONH(CH 2 CH 2 O)-H
  • ultraviolet light absorbing compounds e.g. F 3 C(CF 2 ) 6 CONH(CH 2 CH 2 O)-H
  • silicone oil e.g. silicone oil
  • ultraviolet light absorbing compounds e.g. F 3 C(CF 2 ) 6 CONH(CH 2 CH 2 O)-H
  • the support for the thermographic 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 and subbed if needs be to improve the adherence to the thereon coated heat-sensitive recording layer.
  • the support may be made of an opacified resin composition.
  • thermosensitive element In a preferred embodiment of the present invention a protective layer is provided for the thermosensitive 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 the 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 the 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.
  • liquid lubricants include silicone oils, synthetic oils, saturated hydrocarbons and glycols.
  • solid lubricants include various higher alcohols such as stearyl alcohol, fatty acids and fatty acid esters.
  • Suitable slipping layer compositions are described, for example, in EP-A 138 483, EP-A 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 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, U.S.A. Coating may proceed from aqueous or solvent media with overcoating of dried, partially dried or undried layers.
  • 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 1.0ms, 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 the thermal printing heads may proceed through a contacting but removable resin sheet or web wherefrom during the 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 or from an intermediary storage means, optionally linked to a digital image work station wherein the image information can be processed to satisfy particular needs.
  • Activation of the heating elements can be power-modulated or pulse-length modulated at constant power.
  • EP-A 654 355 describes a method for making an image by image-wise heating by means of a thermal head having energizable heating elements, wherein the activation of the heating elements is executed duty cycled pulsewise. When used in thermographic recording operating with thermal printheads the thermographic recording materials are 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 recording material can also be carried out using an electrically resistive ribbon incorporated into the material.
  • Image- or pattern-wise heating of the thermographic recording 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 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, 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.
  • thermosensitive element The following examples and comparative examples illustrate the present invention.
  • the percentages and ratios used in the examples are by weight unless otherwise indicated.
  • the following ingredients were used in the thermosensitive element in addition to those mentioned above:
  • 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 (a horizontal bead mill from BACKOFEN) for 2 hours to produce the final tone modifier dispersion containing: 20% of T01 and 8.8% of gelatin.
  • DYNOMILLTM a horizontal bead mill from BACKOFEN
  • the coating dispersions for the thermographic recording materials of COMPARATIVE EXAMPLE 1 and INVENTION EXAMPLES 1 & 2 were prepared by first dissolving 1.927g of K7598 in deionized water at 38°C (for the quantity of water see table 1), then adding with stirring to the warm K7598 solution: first 19.0g of the silver behenate dispersion, then 5.9g of a 30% dispersion of polymer latex nr. 1 and 5.68g of the tone modifier dispersion as flakes followed by 5 minutes stirring, then the reducing agent (s) (for quantities and types see table 1) dissolved in 1.71g of ethanol and finally 1.310g of a 3.7% by weight solution of formaldehyde to produce the corresponding coating dispersions.
  • thermosensitive elements of the thermographic recording materials of COMPARATIVE EXAMPLES 1 and INVENTION EXAMPLES 1 & 2 with the compositions given in table 2.
  • Nr 1 4.68 0.47 R02 1.15 2.55 1.85 0.05 1.18 2 4.65 0.47 R03 0.70 2.53 1.84 0.05 1.17
  • 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 recording materials of COMPARATIVE EXAMPLES 1 and INVENTION EXAMPLES 1 & 2.
  • NCV values were determined at optical densities (D) with a visual filter of 1, 2 and 3 for the fresh materials, the same materials after being heated at 35°C in a relative humidity of 80% for 3 days and the same materials after being exposed in the light box described below at 30°C in a relative humidity of 85% for 3 days for the materials of COMPARATIVE EXAMPLE 1 and INVENTION EXAMPLES 1 & 2.
  • the NCV-values obtained are summarized in table 3 below. Comparative Example Nr.
  • thermographic recording materials of INVENTION EXAMPLES 1 & 2 exposed in the light box for 3 days at 30°C in 85% relative humidity are clearly superior to those of the thermographic recording material of COMPARATIVE EXAMPLE 1 with a reducing agent according to the teaching of US-P 5, 582, 953 and those for prints stored in the dark for 3 days at 35°C in 80% relative humidity are comparable therewith. It is therefore evident that prints made with the thermographic recording materials using the novel reducing agents of the present invention exhibit superior colour neutrality to prior art materials.
  • thermographic recording materials of COMPARATIVE EXAMPLE 1 and INVENTION EXAMPLES 1 & 2 were evaluated on the basis of the observed changes in NCV-values and minimum density, ⁇ D min , upon heating the prints at 35°C in a relative humidity of 80% for 3 days in the dark. The results of these tests are als given in table 4.
  • the stability of the image background of the prints made with the thermographic recording materials of COMPARATIVE EXAMPLE 1 and INVENTION EXAMPLES 1 & 2 was evaluated on the basis of the change in NCV-values and minimum (background) density and maximum 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 VOTSCH conditioning cupboard set at 30°C and a relative humidity 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 4 The results are summarized in table 4.
  • thermosensitive element Preparation of the thermosensitive element
  • thermosensitive element with the compositions summarized in tables 5 and 6 below for COMPARATIVE EXAMPLE 2 and INVENTION EXAMPLES 3 to 6 respectively: Comparative example number AgB [g/m 2 ] B79 [g/m 2 ] Oil [g/m 2 ] T01 [g/m 2 ] T02 [g/m 2 ] CR01 [g/m 2 ] S01 [g/m 2 ] S02 [g/m 2 ] S03 [g/m 2 ] 2 4.91 19.62 0.045 0.27 0.14 0.989 0.35 0.16 0.13 Invention Example nr AgB [g/m 2 ] B79 [g/m 2 ] Oil [g/m 2 ] T01 [g/m 2 ] T02 [g/m 2 ] reducing
  • thermographic recording materials of COMPARATIVE EXAMPLE 2 and INVENTION EXAMPLES 3 to 6 were evaluated as described above for COMPARATIVE EXAMPLE 1 and INVENTION EXAMPLES 1 & 2 except that the archivability tests were carried out for 3 days at 57°C in a relative humidity of 34% instead of 3 days at 35°C in a relative humidity of 80%.
  • the NCV-values for the thermographic recording materials of COMPARATIVE EXAMPLE 2 and INVENTION EXAMPLES 3 to 6 for fresh prints and prints exposed in the light box for 3 days at 30°C in a relative humidity of 85% are given in table 7 below. Comparative Example Nr.
  • thermographic recording material of COMPARATIVE EXAMPLE 2 with a reducing agent according to the teaching of US-P 5,582,953 is greater than that observed for the thermographic recording material of INVENTION EXAMPLE 4 and substantially greater than that observed for the thermographic recording materials of INVENTION EXAMPLES 3, 5 and 6 for which there is little discernible change in colour neutrality.
  • NCV-value in terms of the visual perception of a viewer is that at a density of 1.0.

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EP19980202551 1997-09-17 1998-07-30 Thermographischen Aufzeichnungsmaterialien Expired - Lifetime EP0903625B1 (de)

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Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1059560A1 (de) * 1999-06-04 2000-12-13 Agfa-Gevaert N.V. Thermographisches Aufzeichnungsmaterial mit verbessertem Bildton
US6211116B1 (en) 1998-06-08 2001-04-03 Agfa-Gevaert Substantially light-insensitive black and white thermographic recording material with improved image tone
EP1245403A1 (de) * 2001-03-29 2002-10-02 Agfa-Gevaert Thermographisches Aufzeichnungsmaterial mit verbessertem Bildton
EP1270255A1 (de) * 2001-06-29 2003-01-02 Agfa-Gevaert Thermographisches Aufzeichnungsmaterial mit verbessertem Bildton
US6693062B2 (en) 2001-06-29 2004-02-17 Agfa-Gevaert Thermographic recording material with improved image tone
US6774084B2 (en) 2001-03-29 2004-08-10 Agfa-Gevaert Thermographic recording material with improved image tone
US7097961B2 (en) 2004-05-17 2006-08-29 Agfa Gevaert Stabilizers for use in substantially light-insensitive thermographic recording materials
US7175977B2 (en) 2003-12-18 2007-02-13 Agfa-Gevaert Stabilizers for use in thermographic recording materials
US7179768B2 (en) 2004-11-05 2007-02-20 Agfa-Gevaert Toning agents for use in thermographic recording materials
US7307041B2 (en) 2004-09-17 2007-12-11 Agfa Healthcare Stabilizers for use in substantially light-insensitive thermographic recording materials
EP2199100A1 (de) 2008-12-22 2010-06-23 Agfa-Gevaert N.V. Sicherheitslaminate für Sicherheitsdokumente

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7294605B2 (en) 2003-12-18 2007-11-13 Agfa-Healthcare Thermographic recording materials containing a mesionic, 1,2,4-triazolium-3-thiolate compound
US7282468B2 (en) 2005-07-18 2007-10-16 Carestream Health Inc. Direct thermographic materials with catechol borate reducing agents

Citations (2)

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Publication number Priority date Publication date Assignee Title
EP0248405A2 (de) * 1986-06-03 1987-12-09 Jujo Paper Co., Ltd. Wärmeempfindliches Aufzeichnungsmaterial
EP0599580A1 (de) * 1992-11-20 1994-06-01 Nippon Paper Industries Co., Ltd. Wärmeempfindliches Aufzeichnungsblatt

Patent Citations (2)

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Publication number Priority date Publication date Assignee Title
EP0248405A2 (de) * 1986-06-03 1987-12-09 Jujo Paper Co., Ltd. Wärmeempfindliches Aufzeichnungsmaterial
EP0599580A1 (de) * 1992-11-20 1994-06-01 Nippon Paper Industries Co., Ltd. Wärmeempfindliches Aufzeichnungsblatt

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6211116B1 (en) 1998-06-08 2001-04-03 Agfa-Gevaert Substantially light-insensitive black and white thermographic recording material with improved image tone
EP1059560A1 (de) * 1999-06-04 2000-12-13 Agfa-Gevaert N.V. Thermographisches Aufzeichnungsmaterial mit verbessertem Bildton
EP1245403A1 (de) * 2001-03-29 2002-10-02 Agfa-Gevaert Thermographisches Aufzeichnungsmaterial mit verbessertem Bildton
US6774084B2 (en) 2001-03-29 2004-08-10 Agfa-Gevaert Thermographic recording material with improved image tone
EP1270255A1 (de) * 2001-06-29 2003-01-02 Agfa-Gevaert Thermographisches Aufzeichnungsmaterial mit verbessertem Bildton
US6693062B2 (en) 2001-06-29 2004-02-17 Agfa-Gevaert Thermographic recording material with improved image tone
US7175977B2 (en) 2003-12-18 2007-02-13 Agfa-Gevaert Stabilizers for use in thermographic recording materials
US7097961B2 (en) 2004-05-17 2006-08-29 Agfa Gevaert Stabilizers for use in substantially light-insensitive thermographic recording materials
US7307041B2 (en) 2004-09-17 2007-12-11 Agfa Healthcare Stabilizers for use in substantially light-insensitive thermographic recording materials
US7179768B2 (en) 2004-11-05 2007-02-20 Agfa-Gevaert Toning agents for use in thermographic recording materials
EP2199100A1 (de) 2008-12-22 2010-06-23 Agfa-Gevaert N.V. Sicherheitslaminate für Sicherheitsdokumente

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