EP0978760B1 - Thermographischen Aufzeichnungsmaterialien - Google Patents

Thermographischen Aufzeichnungsmaterialien Download PDF

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Publication number
EP0978760B1
EP0978760B1 EP19990202007 EP99202007A EP0978760B1 EP 0978760 B1 EP0978760 B1 EP 0978760B1 EP 19990202007 EP19990202007 EP 19990202007 EP 99202007 A EP99202007 A EP 99202007A EP 0978760 B1 EP0978760 B1 EP 0978760B1
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EP
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Prior art keywords
recording material
substantially light
thermographic recording
insensitive
heat source
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EP19990202007
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English (en)
French (fr)
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EP0978760A1 (de
Inventor
Johan Loccufier
Bart Horsten
Peter Slabbinck
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Agfa Gevaert NV
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Agfa Gevaert NV
Agfa Gevaert AG
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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
    • G03C1/49827—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
    • 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
    • G03C2200/00—Details
    • G03C2200/45—Polyhydroxybenzene

Definitions

  • the present invention concerns black and white substantially light-insensitive thermographic recording materials 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.
  • Most of the "direct" thermographic recording materials are of the chemical type in which upon heating an irreversible chemical reaction takes place and a coloured image is produced.
  • 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 and the electron donor is a polyhydric aromatic compound of formula (I): wherein R is an alkyl group with 18 to 35 carbon atoms, wherein R 1 is a C 18 - to C 35 -alkyl group, n is an integer of 2 or 3, -X- is -CH 2 -, -CO 2 -, -CO-, -O-, -CONH-, -CO(R')N- (wherein R' is a C 18 - to C 35 -group), -SO 2 -, -SO 3 - or -SO 2 NH-.
  • Example 4 concerns a thermosensitive recording material with a colour-developing layer containing silver aluminium double salt of oct
  • 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), which is the same as formula (I) of EP-A 248 405.
  • JIS Japanese Industrial Standard
  • thermosensitivity of organic silver salt/reducing agent systems is dependent upon the choice of reducing agent.
  • increased thermosensitivity is generally associated with poorer image gradation i.e. dependence of image density upon applied thermal energy, reduced stability and poorer image colour.
  • reducing agents which increase the thermosensitivity of organic silver salt/reducing agent systems without substantially affecting the gradation, stability and image colour of prints made therewith.
  • thermographic recording materials with increased thermosensitivity without significantly affecting the gradation, stability and image colour of prints made therewith.
  • thermographic recording materials containing novel 3,4-dihydroxyphenyl compounds exhibit increased thermosensitivity without significantly affecting the gradation, stability and image colour of prints made therewith. In fact there is even a marginal improvement in image colour.
  • a recording process comprising the steps of: (i) providing the above-described substantially light-insensitive black and white monosheet thermographic recording material; (ii) bringing an outermost layer of the recording material into proximity with a heat source; (iii) applying heat from a heat source image-wise to the recording material while maintaining proximity to the heat source to produce an image; and (iv) removing the recording material from the heat source.
  • the heat source is a thermal head.
  • the organic reducing agent used in the thermographic recording materials of the present invention is a 2,3,4-trihydroxyphenyl-compound represented by formula (I).
  • Hammett substituent constants are, for example, listed on pages 28 and 29 of Advances in Linear Free Energy Relationships, edited by N. B. Chapman and J. Shorter and published by Plenum Press, London in 1972.
  • R groups are formyl, oxo-alkyl, oxo-aryl, cyano, carbamido, diphenoxyphosphoryl, alkylsulfinyl, alkylsulfonyl and sulfonylamino groups.
  • Preferred reducing agents for use in the present invention are selected from the group consisting of: consisting of: consisting of: consisting of: 2,3,4-trihydroxy-acetophenone, 2,3,4-trihydroxy-propionophenone, 2,3,4-trihydroxybenzaldehyde and 2,3,4-trihydroxybenzonitrile.
  • Compounds according to formula(I) are long known, the synthesis of a wide range of 2,3,4-trihydroxy-phenyl-oxo-derivatives, for example being described in Beilsteins Handbuch der Organischen Chemie, Vieri Auflage, Achter Band, Springer Verlag, Berlin (1925): p. 388, 393, 398, 399, 400, 417, 684 and 685.
  • 2,3,4-trihydroxy-benzaldehyde, 2',3',4'-trihydroxyacetophenone, 2,3,4-trihydroxy-benzophenone are all commercially available from Aldrich and can be used to produce other derivatives such as 2,3,4-trihydroxybenzonitrile by methods known to synthetic chemists.
  • auxiliary reducing agents are e.g. hydroquinone or catechol substituted with strongly electron-withdrawing groups such as sulfonic acid groups; hydrazides such as disclosed in EP-A 762 196, sulfonyl hydrazide reducing agents such as disclosed in US-P 5,464,738; trityl hydrazides and formyl-phenyl-hydrazides such as disclosed in US-P 5,496,695; trityl hydrazides and formyl-phenyl-hydrazides with diverse auxiliary reducing agents such as disclosed in US-P 5,545,505, US-P 5,545,507 and US-P 5,558,983; acrylonitrile compounds as disclosed in US-P 5,545,515 and US-P 5,635,339; 2-substituted malondialdehy
  • thermographic material comprises a support and a thermosensitive element which further contains a 3,4-dihydroxyphenyl compound with ethyl 3,4-dihydroxybenzoate, butyl 3,4-dihydroxybenzoate and 3,4-dihydroxybenzoic acid being particularly preferred.
  • a substituted or unsubstituted alkyl group with 12 carbon atoms or less includes: methyl, ethyl, n-propyl, isopropyl, n-butyl, tertiary butyl, secondary butyl, n-pentyl, n-hexyl, cyclohexyl, n-heptyl, 2-ethylhexyl, n-octyl, n-nonyl, n-decyl, n-undecyl and n-dodecyl groups.
  • thermographic recording material comprising a thermosensitive element including a substantially light-insensitive organic silver salt, a reducing agent according to formula (I) 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 reducing agent according to formula (I) are in thermal working relationship with one another i.e. during the thermal development process the reducing agent according to formula (I) 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.
  • 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.
  • 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 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.
  • 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.
  • 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.
  • stabilizers and antifoggants may be incorporated into the thermographic recording materials of the present invention.
  • Suitable stabilizers compounds are unsaturated carbocyclic or heterocyclic compounds substituted with a -SA group where A is hydrogen, a counterion to compensate the negative charge of the thiolate group or a group forming a symmetrical or an asymmetrical disulfide. for use in the present invention may be further substituted, which substitution also includes the atoms necessary to form an annulated unsaturated carbocyclic or heterocyclic ring system.
  • Preferred substituents include acylamido, aryl-SO 2 NH-, alkyl-SO 2 NH-, aryl-NHSO 2 -, alkyl-NHSO 2 -, arylamino, alkyl, aryl, nitro and cyano groups and halogen atoms.
  • Preferred stablizer compounds used in the present invention have an unsaturated 5- or 6-membered ring. Particularly suitable compounds are represented by formula (II): where Q are the necessary atoms to form a 5- or 6-membered aromatic heterocyclic ring, A is selected from hydrogen, a counterion to compensate the negative charge of the thiolate group or a group forming a symmetrical or an asymmetrical disulfide.
  • 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.
  • 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 material may contain other additives such as free fatty acids, 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
  • ultraviolet light absorbing compounds
  • the support for the thermographic 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.
  • Suitable slipping layer . compositions are described, for example, in 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, USA. 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.
  • thermographic recording 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.
  • 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 material can also be carried out using an electrically resistive ribbon incorporated into the material.
  • Image- or pattern-wise heating of the thermographic material may also proceed by means of pixel-wise modulated ultra-sound.
  • 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:
  • thermosensitive element Preparation of the thermosensitive element
  • thermosensitive element with the compositions summarized in table 1 below: Comparative example nr AgBeh coverage [g/m 2 ] reducing agent BR 18 [g/m 2 ] Oil [g/m 2 ] T01 [g/m 2 ] S01 [g/m 2 ] S02 [g/m 2 ] type [g/m 2 ] 1 5.35 CR01 1.091 5.35 20.4 0.300 0.128 0.117 2 5.35 CR02 1.274 5.35 20.4 0.300 0.128 0.117 Invention example nr 1 5.40 R02 1.126 5.40 20.6 0.302 0.130 0.118
  • 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 6.5ms (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 & 2 and INVENTION EXAMPLE 1.
  • the maximum and minimum densities of the prints given in table 2 were measured through a visible or blue filter with a MACBETHTM TR924 densitometer in the grey scale step corresponding to data levels of 64 and 0 respectively and are given in table 2.
  • the numerical gradation value (NGV) corresponding with the quotient of the fraction [2.5 - (1.0 + D min )]/[E 2.5 - E (1.0 + Dmin) ] was determined, wherein E 2.5 is the energy in Joule applied in a dot area of 87 ⁇ m x 87 ⁇ m of the imaging layer that obtains by the energy an optical density value of 2.5, and E (1.0 + Dmin) is the energy in Joule applied in a dot area of the imaging layer material that obtains by the energy an optical density value of (1.0 + D min ).
  • the applied energy in Joule is actually the electrical input energy measured for each resistor of the thermal head.
  • the NGV's for the thermographic recording materials of COMPARATIVE EXAMPLES 1 & 2 and INVENTION EXAMPLE 1 are given in table 2.
  • the light stability of the image background of the prints made with the thermographic recording materials of COMPARATIVE EXAMPLES 1 & 2 and INVENTION EXAMPLE 1 was evaluated on the basis CIELAB-values.
  • the CIELAB-values were determined by spectrophotometric measurements according to ASTM Norm E179-90 in a R(45/0) geometry with evaluation according to ASTM Norm E308-90.
  • the light box test consisted of first heating the thermographic materials of COMPARATIVE EXAMPLES 1 & 2 and INVENTION EXAMPLE 1 for 2 days at 57°C and 34% relative humidity and then exposing them on top of the white PVC window of a specially constructed light-box for 3 days in a V ⁇ TSCH conditioning cupboard set at 30°C and a relative humidity of 80%. 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.
  • the a* and b* CIELAB of the thermographic recording materials of COMPARATIVE EXAMPLES 1 & 2 and INVENTION EXAMPLE 1 determined after the light box test are summarized in table 2.
  • Colour neutrality on the basis of CIELAB-values corresponds to a* and b* values of zero, with a negative a*-value indicating a greenish image-tone becoming greener as a* becomes more negative, a positive a*-value indicating a reddish image-tone becoming redder as a* becomes more positive, a negative b*-value indicating a bluish image-tone becoming bluer as b* becomes more negative and a positive b*-value indicating a yellowish image-tone becoming yellower as b* becomes more positive.
  • thermographic recording material of INVENTION EXAMPLE 1 and COMPARATIVE EXAMPLES 1 & 2 show that the thermographic recording material of INVENTION EXAMPLE 1, incorporating a novel reducing agent in the thermographic recording material according to the present invention, is clearly more thermosensitive than the thermographic recording materials of COMPARATIVE EXAMPLES 1 & 2, as evidenced by its higher D max value.
  • thermographic recording material of INVENTION EXAMPLE 1 exhibited a gradation (NGV value) comparable or superior to that of the thermographic recording materials of COMPARATIVE EXAMPLES 1 & 2 and comparable CIELAB a* and b* values.
  • thermosensitive elements of the thermographic recording materials of COMPARATIVE EXAMPLE 3 to 5 and INVENTION EXAMPLES 2 and 3 were prepared as described for COMPARATIVE EXAMPLES 1 & 2 and INVENTION EXAMPLE 1.
  • the compositions of the thermosensitive elements are given in table 3 below.
  • thermographic recording materials of COMPARATIVE EXAMPLES 3 to 5 and INVENTION EXAMPLES 2 and 3 were evaluated as described above for COMPARATIVE EXAMPLES 1 & 2 and INVENTION EXAMPLE 1. The results are given in table 4 below.
  • thermographic evaluation of the thermographic recording materials of INVENTION EXAMPLE 2 and 3 and COMPARATIVE EXAMPLES 3 to 5 show that the thermographic recording material of INVENTION EXAMPLES 2 and 3, incorporating novel reducing agents in the thermographic recording material according to the present invention, exhibit a higher thermal sensitivity (i.e.
  • thermographic recording materials of INVENTION EXAMPLES 2 & 3 exhibit comparable or more neutral CIELAB a*- and b*-values after the light box test.
  • thermosensitive elements of the thermographic recording materials of COMPARATIVE EXAMPLE 6 and INVENTION EXAMPLES 4 to 7 were prepared as described for COMPARATIVE EXAMPLES 1 & 2 and INVENTION EXAMPLE 1.
  • the compositions of the thermosensitive elements are given in table 5 below.
  • thermographic evaluation of the thermographic recording materials of INVENTION EXAMPLE 4 to 7 and COMPARATIVE EXAMPLE 6 show that the thermographic recording material of INVENTION EXAMPLES 4 to 7, incorporating novel reducing agents in the thermographic recording material according to the present invention, have higher thermosensitivities (i.e. higher D max values) and higher gradations (i.e. higher NGV values) than those of the thermographic recording material of COMPARATIVE EXAMPLE 6.
  • thermosensitive elements of the thermographic recording materials of COMPARATIVE EXAMPLE 7 to 9 and INVENTION EXAMPLES 8 & 9 were prepared as described for COMPARATIVE EXAMPLES 1 & 2 and INVENTION EXAMPLE 1.
  • the compositions of the thermosensitive elements are given in table 7 below.
  • thermographic evaluation of the thermographic recording materials of INVENTION EXAMPLE 8 and 9 and COMPARATIVE EXAMPLES 7 to 9 show that the thermographic recording material of INVENTION EXAMPLES 8 & 9, incorporating novel reducing agents in the thermographic recording material according to the present invention, exhibit higher thermosensitivities (i.e. D max values) and high gradations (i.e. higher NGV values) than those of the thermographic recording materials of COMPARATIVE EXAMPLES 7 to 9 using reducing agents according to the teachings of US-P 5,582,953, EP-A 903 625 and EP-A 599 369 respectively.

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Claims (8)

  1. Ein wesentlich lichtunempfindliches thermografisches Schwarzweiß-Einzelbogen-Aufzeichnungsmaterial mit einem Träger und einem wärmeempfindlichen Element, das ein wesentlich lichtunempfindliches organisches Silbersalz, eine 1,2-Dihydroxyphenyl-Verbindung in thermischer wirksamer Beziehung dazu und ein Bindemittel enthält, dadurch gekennzeichnet, daß die 1,2-Dihydroxyphenyl-Verbindung Formel (I) entspricht :
    Figure 00220001
    in der bedeuten :
    n 0 oder 1,
    R -(C=O)R1, -(C=O)NR1R2, -CN, -SO3R2, -SO2R2, -SOR2, -SO2NR2R3, -PO3R2R3 oder eine Oxoarylgruppe,
    R1 ein Wasserstoffatom oder eine gegebenenfalls substituierte Alkylgruppe mit 12 oder weniger Kohlenstoffatomen oder eine Arylgruppe,
    R2 und R3 unabhängig voneinander ein Wasserstoffatom, eine gegebenenfalls substituierte Alkylgruppe oder eine gegebenenfalls substituierte Arylgruppe, und
    wobei R1 und R2 zusammen die zum Schließen eines heterocyclischen Ringes benötigten Atome bedeuten dürfen, und
    R2 und R3 zusammen die zum Schließen eines heterocyclischen Ringes benötigten Atome bedeuten dürfen.
  2. Wesentlich lichtunempfindliches thermografisches Schwarzweiß-Einzelbogen-Aufzeichnungsmaterial nach Anspruch 1, dadurch gekennzeichnet, daß in der Verbindung der Formel (I) n O ist und R aus der Gruppe bestehend aus einer Formyl-, Oxoalkyl-, Oxoaryl-, Cyan-, Carbamid-, Diphenoxyphosphoryl-, Alkylsulfinyl-, Alkylsulfonyl- und Sulfonylaminogruppe gewählt wird.
  3. Wesentlich lichtunempfindliches thermografisches Schwarzweiß-Einzelbogen-Aufzeichnungsmaterial nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß das Reduktionsmittel aus der Gruppe bestehend aus 2,3,4-Trihydroxyacetophenon, 2,3,4-Trihydroxypropionophenon, 2,3,4-Trihydroxybenzaldehyd und 2,3,4-Trihydroxybenzonitril gewählt wird.
  4. Wesentlich lichtunempfindliches thermografisches Schwarzweiß-Einzelbogen-Aufzeichnungsmaterial nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß das wärmeempfindliche Element weiterhin zumindest eine Polycarbonsäure und/oder ein Polycarbonsäureanhydrid in einem Molverhältnis von zumindest 15, bezogen auf das wesentlich lichtunempfindliche organische Silbersalz und in thermischer wirksamer Beziehung dazu, enthält.
  5. Wesentlich lichtunempfindliches thermografisches Schwarzweiß-Einzelbogen-Aufzeichnungsmaterial nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß das wärmeempfindliche Element mit einer Schutzschicht überzogen ist.
  6. Wesentlich lichtunempfindliches thermografisches Schwarzweiß-Einzelbogen-Aufzeichnungsmaterial nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß das wesentlich lichtunempfindliche organische Silbersalz ein Silbersalz einer organischen Carbonsäure ist.
  7. Ein durch die nachstehenden Schritte gekennzeichnetes Aufzeichnungsverfahren : (i) Bereitstellen eines wesentlich lichtunempfindlichen thermografischen Schwarzweiß-Einzelbogen-Aufzeichnungsmaterials nach einem der Ansprüche 1 bis 6, (ii) Anordnen einer Außenschicht des Aufzeichnungsmaterials in der Nähe einer Heizquelle, (iii) bildmäßige Beaufschlagung des Aufzeichnungsmaterials mit von einer Heizquelle gelieferter Wärme zur Herstellung eines Bildes, wobei das Aufzeichnungsmaterial in der Nähe der Heizquelle gehalten wird, und (iv) Entfernen des Aufzeichnungsmaterials von der Heizquelle.
  8. Verfahren nach Anspruch 7, dadurch gekennzeichnet, daß die Heizquelle ein Thermokopf ist.
EP19990202007 1998-08-07 1999-06-23 Thermographischen Aufzeichnungsmaterialien Expired - Lifetime EP0978760B1 (de)

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US6774084B2 (en) 2001-03-29 2004-08-10 Agfa-Gevaert Thermographic recording material with improved image tone
EP1245404A1 (de) * 2001-03-29 2002-10-02 Agfa-Gevaert Thermographisches Aufzeichnungsmaterial, das Ausdrucke mit guter Bilddichte und gutem Bildton und verbesserter Archivierbarkeit ergibt
US6798439B2 (en) 2001-10-02 2004-09-28 Agfa-Gevaert Thermal recording by means of a flying spot

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