EP1006405B1 - Thermographisches Schwarz-Weiss-Aufzeichnungsmaterial mit verbessertem Bildton - Google Patents

Thermographisches Schwarz-Weiss-Aufzeichnungsmaterial mit verbessertem Bildton Download PDF

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Publication number
EP1006405B1
EP1006405B1 EP99204003A EP99204003A EP1006405B1 EP 1006405 B1 EP1006405 B1 EP 1006405B1 EP 99204003 A EP99204003 A EP 99204003A EP 99204003 A EP99204003 A EP 99204003A EP 1006405 B1 EP1006405 B1 EP 1006405B1
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EP
European Patent Office
Prior art keywords
recording material
thermographic recording
thermographic
substantially light
heat source
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EP99204003A
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English (en)
French (fr)
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EP1006405A1 (de
Inventor
Bartholomeus Horsten
Guy Jansen
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
    • G03C1/4989—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
    • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
    • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
    • G03C1/30—Hardeners
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/494—Silver salt compositions other than silver halide emulsions; Photothermographic systems ; Thermographic systems using noble metal compounds
    • G03C1/498—Photothermographic systems, e.g. dry silver
    • G03C1/49836—Additives
    • G03C1/49863—Inert additives, e.g. surfactants, binders

Definitions

  • the present invention relates to improved substantially light-insensitive black and white monosheet thermographic recording materials.
  • Thermal imaging or thermography is a recording process wherein images are generated by the use of thermal energy.
  • direct thermal thermography a visible image pattern is formed by image-wise heating of a recording material containing matter that by chemical or physical process changes colour or optical density.
  • Most of the "direct" thermographic recording 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.
  • thermosensitive or other hardenable layers in thermographic materials can be hardened with organic or inorganic hardening agents such as aldehydes and blocked aldehydes, ketones, carboxylic and carbonic acid derivatives, sulfonate esters, sulfonyl halides and vinyl sulfonyl ethers, active halogen compounds, epoxy compounds, aziridines, active olefins, isocyanates, carbodiimides, mixed function hardeners and polymeric hardeners such as oxidized polysaccharides like dialdehyde starch and oxy-guargum and the like.
  • this disclosure is merely an invitation to experiment, because almost all hardening agents known for gelatino silver halide emulsion photographic-sensitive materials processed by wet treatment are enumerated and there is no example using them.
  • WO 95/12495 discloses a method of recording an image by image-wise heating a recording material, the recording material comprising on the same side of a support, called the heat sensitive side, (1) one or more layers comprising an imaging composition essentially consisting of (i) a substantially light-insensitive organic silver salt being in thermal working relationship with (ii) a reducing agent, and (2) at the same side covering the imaging composition a protective layer, characterized in that the image-wise heating proceeds with a thermal head contacting the heat-sensitive side and through the protective layer mainly comprising a cured polymer or cured polymer composition.
  • the protective layer contains hydrophilic polymers having active hydrogen atoms at least part of which has reacted with hardening agents selected from the group consisting of polyisocyanates, polyepoxides, aldehydes and hydrolysed tetraalkyl orthosilicates.
  • US 5,468,603 discloses a thermographic emulsion layer containing an organic silver salt, a polyisocyanate, a binder, e.g. BUTVARTM B-79, and a large selection of reducing agents, with a sterically hindered bisphenols being preferred, provided with a protective layer comprising a polymeric fluorinated surfactant.
  • DESMODURTM 3300 is disclosed in US 5,468,603 for photothermographic emulsion layers.
  • US 5,468,228 discloses a thermographic emulsion layer containing an organic silver salt, a binder, e.g. BUTVARTM B-79, a substituted propene compound and a large selection of reducing agents, with a sterically hindered bisphenosl being preferred.
  • DESMODURTM 3300 is disclosed in US 5,468,228 for photothermographic emulsion layers.
  • thermographic materials from solvents with protective layers it is desirable for economic and logistical reasons to coat the organic silver salt-containing layer simultaneously with a protective layer. This requires hardening of both layers to prevent significant interfacial mixing thereof. However, the use of such hardeners was found to affect significantly the image gradation of the resulting materials.
  • thermosensitive element It is therefore another object of the present invention to provide a substantially light-insensitive black and white thermographic recording materials which upon printing exhibits an image gradation which is not significantly affected by the thermosensitive element being hardened.
  • thermosensitive element Surprisingly it has been found that this adverse effect on image gradation upon hardening the thermosensitive element could be avoided by the use of 1,2-dihydroxy-benzene derivatives as reducing agents in combination with specific polyisocyanates as hardeners, the gradation of substantially light-insensitive black and white monosheet thermographic recording materials based on substantially light-insensitive organic silver salts and reducing agents therefor being substantially unaffected by the hardening process.
  • thermosensitive black and white monosheet thermographic recording material comprising a support and a thermosensitive element provided with a protective layer, the thermosensitive element containing a substantially light-insensitive organic silver salt, a 1,2-dihydroxy-benzene derivative in thermal working relationship therewith and a first polymer having active hydrogen atoms at least part of which has reacted with a first polyisocyanate selected from the group consisting of: hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanat, naphthylene diisocyanate and triphenylmethane-p,p',p"-trityl triisocyanate; and the protective layer being exclusive of fluorine-containing compounds.
  • a recording process is further provided according to the present invention comprising the steps of: (i) bringing an outermost layer of the above-mentioned thermographic recording material in proximity with a heat source; and (ii) applying heat from the heat source imagewise to the recording material while maintaining proximity to the heat source to produce an image; and (iii) removing the recording material from the heat source.
  • the heat source is a thermal head with a thin film thermal head being particularly preferred.
  • 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.
  • 1,2-dihydroxy-benzene derivatives are compounds having a benzene ring substituted with two hydroxy groups ortho to one another.
  • a polymer having active hydrogen atoms is meant a polymer having substituents with hydrogen atoms which readily react such as hydroxy groups, thiol groups, carboxy groups, -N-H groups, amino groups, amido groups etc.
  • polyisocyanate is meant a compound having at least two isocyanate groups which may or may not be blocked with groups which are readily displaced during a hardening process, wherein the polyisocyanate reacts with the active hydrogen atoms of a polymer having active hydrogen atoms.
  • fluorine-containing compounds includes all compounds containing fluorine and all compounds with fluorine-containing compounds as impurities and includes polymeric fluorinated surfactants such as disclosed in US 5,468,603.
  • US 5,468,603 discloses a polymeric fluorinated surfactant containing at least three different groups within the polymer chain derived from reactive monomers, the monomers comprising: (a) a fluorinated, ethylenically unsaturated monomer; (b) a hydroxyl-containing, ethylenically unsaturated monomer; and (c) a polar, ethylenically unsaturated monomer; which is produced by addition copolymerization.
  • Suitable organic reducing agents according to the present invention are 1,2-dihydroxybenzene derivatives, such as catechol; 3-(3,4-dihydroxyphenyl) propionic acid; 3,4-dihydroxybenzoic acid and its esters; gallic acid and its esters e.g. methyl gallate, ethyl gallate, propyl gallate; tannic acid; 1,2-dihydroxy-naphthalene and 2,3-dihydroxynaphthalene.
  • 1,2-dihydroxybenzene derivatives such as catechol; 3-(3,4-dihydroxyphenyl) propionic acid; 3,4-dihydroxybenzoic acid and its esters; gallic acid and its esters e.g. methyl gallate, ethyl gallate, propyl gallate; tannic acid; 1,2-dihydroxy-naphthalene and 2,3-dihydroxynaphthalene.
  • the 1,2-dihydroxybenzene derivative is a 3,4-dihydroxybenzoic acid derivative.
  • alkyl and aryl groups can also be substituted with one or more groups selected from hydroxy, cyano, thiol and halogen.
  • Preferred reducing agents for use in the present invention are selected from the group consisting of: ethyl 3,4-dihydroxybenzoate, butyl 3,4-dihydroxybenzoate, 3,4-dihydroxybenzonitrile, 2,3,4-trihydroxy-acetophenone, 2,3,4-trihydroxy-propionophenone, 2,3,4-trihydroxybenzaldehyde, 2,3,4-trihydroxy-butyrophenone and 2,3,4-trihydroxybenzonitrile.
  • Combinations of reducing agents may also be used that on heating become reactive partners in the reduction of the substantially light-insensitive organic silver salt.
  • the first polycyanate used in the thermosensitive elements of the substantially light-insensitive black and white monosheet thermographic recording material of the present invention is selected from the group consisting of: hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanat, naphthylene diisocyanate and triphenylmethane-p,p',p"-trityl triisocyanate.
  • Any polyisocyanate which reacts with polymers having active hydrogen atoms may be used for the second polyisocyanate e.g. a polyisocyanate with free isocyanate-groups or one with a blocking group to prevent reaction at room temperature.
  • Suitable polyisocyanates include:
  • the first and second polyisocyanates may be the same or different.
  • thermosensitive element contains a substantially light-insensitive organic silver salt, a 1,2-dihydroxybenzene derivative in thermal working relationship therewith and a polymer having active hydrogen atoms at least part of which has reacted with a first polyisocyanate.
  • 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 is in reactive association with the 1,2-dihydroxybenzene derivative i.e. during the thermal development process the 1,2-dihydroxybenzene derivative must be present in such a way that it is able to diffuse to the particle of substantially light-insensitive organic silver salt so that reduction to silver can occur.
  • Preferred substantially light-insensitive organic silver salts for use in the thermosensitive element of the substantially light-insensitive black and white thermographic recording material used in the present invention are silver salts of aliphatic carboxylic acids known as fatty acids, wherein the aliphatic carbon chain has preferably at least 12 C-atoms, which silver salts are also called "silver soaps". Combinations of different organic silver salts may also be used in the imaging materials of the present invention.
  • thermosensitive element preferably further contains a so-called toning agent known from thermography or photothermography.
  • Suitable toning agents are the phthalimides and phthalazinones within the scope of the general formulae described in US-P 4,082,901. Further reference is made to the toning agents described in US-P 3,074,809, 3,446,648 and 3,844,797.
  • Other particularly useful toning agents are the heterocyclic toner compounds of the benzoxazine dione or naphthoxazine dione type as disclosed in GB-P 1,439,478, US-P 3,951,660 and US-P 5,599,647.
  • the first polymer having active hydrogen atoms of the thermosensitive element and the second polymer having active hydrogen atoms of the protective layer may be all kinds of natural, modified natural or synthetic resins or mixtures of such resins, in which the particles of organic silver salt can be dispersed homogeneously either in aqueous or solvent media: e.g. cellulose derivatives such as ethylcellulose, cellulose esters, e.g.
  • an aldehyde preferably polyvinyl butyral
  • polyacrylamide, polymethacrylamide, polyacrylic acid, polymethacrylic acid, proteinaceous binders such as gelatin, modified gelatins such as phthaloyl gelatin, polysaccharides, such as starch, gum arabic and dextran
  • the first polymer having active hydrogen atoms is selected from the group consisting of polyvinyl alcohol, polyvinyl acetals and proteinaceous binders.
  • the binder to organic silver salt weight ratio in the thermosensitive element is preferably in the range of 0.2 to 6, and the thickness of the thermosensitive element is preferably in the range of 5 to 50 ⁇ m.
  • stabilizers and antifoggants may be incorporated into the substantially light-insensitive black and white thermographic recording material used in the present invention.
  • Suitable stabilizers compounds for use in the present invention 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.
  • Such stabilizers may be further substituted, which substitution also includes the atoms necessary to form an annulated unsaturated carbocyclic or heterocyclic ring system.
  • 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.
  • the substantially light-insensitive black and white thermographic recording material used in 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.
  • the substantially light-insensitive black and white thermographic recording material may contain other additives such as free fatty acids, antistatic agents, e.g. non-ionic antistatic agents, 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, silicone oil, ultraviolet light absorbing compounds, white light reflecting and/or ultraviolet radiation reflecting pigments, silica, and/or optical brightening agents.
  • the support of the substantially light-insensitive black and white thermographic recording material used in the present invention may be transparent or translucent and is preferably a thin flexible carrier made 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 thermosensitive element.
  • the support may be dyed or pigmented to provide a transparent coloured background for the image.
  • protective layer contains a second polymer having active hydrogen atoms and a second polyisocyanate.
  • 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.
  • Fluorine-containing compounds are undesirable in the protective layer, because at the high temperatures obtained in the protective layer during the thermal development such compounds react with other ingredients and/or degrade to volatile fluorine-containing compounds which attack the thermal head thereby considerably reducing its operating lifetime.
  • 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.
  • Solid or liquid lubricants or combinations thereof are suitable for improving the slip characteristics of the thermographic recording materials according to the present invention.
  • Solid lubricants which can be used according to the present invention are polyolefin waxes, ester waxes, polyolefin-polyether block copolymers, amide waxes, polyglycols, fatty acids, fatty alcohols, natural waxes and solid phosphoric acid derivatives.
  • Preferred solid lubricants are thermomeltable particles such as those described in WO 94/11199.
  • Liquid lubricants which can be used according to the present invention according to the present invention are fatty acid esters such as glycerine trioleate, sorbitan monooleate and sorbitan trioleate, silicone oil derivatives and phosphoric acid derivatives.
  • the protective layer of the recording material according to the present invention may comprise a matting agent.
  • Suitable matting agents are described in WO 94/11198 and include e.g. talc particles and optionally protrude from the protective layer.
  • thermographic recording materials used in the present invention may also contain antihalation or acutance dyes which absorb infra-red light, for absorption by a dye which converts the absorbed infra-red light into heat, which has passed through the thermosensitive element thereby preventing its reflection.
  • antihalation or acutance dyes which absorb infra-red light, for absorption by a dye which converts the absorbed infra-red light into heat, which has passed through the thermosensitive element thereby preventing its reflection.
  • Such dyes may be incorporated into the thermosensitive element or in any other layer of the recording material of the present invention.
  • any layer of the substantially light-insensitive black and white thermographic recording material used in 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.
  • Direct thermal 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.
  • an infra-red heat source for example with a Nd-YAG laser or other infra-red laser
  • 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 imaging 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 imaging can be used for the production of transparencies and reflection type prints.
  • Application of the present invention is envisaged in the fields of both graphics images requiring high contrast images with a very steep dependence of print density upon applied dot energy and continuous tone images requiring a weaker dependence of print density upon applied dot energy, such as required in the medical diagnostic field.
  • thermographic recording materials on a white opaque base are used, whereas in the medical diagnostic field black-imaged transparencies are widely used in inspection techniques operating with a light box.
  • thermosensitive element Preparation of the thermosensitive element
  • thermosensitive element with the compositions in table 1 below: Comparative example 1 Invention example 1 Invention example 2 Invention example 3 Invention example 4 Invention example 5 AgBeh coverage [g/m 2 ] 6.32 6.32 6.32 6.32 6.32 6.32 6.32 reducing agent types R01/R02 R01/R02 R01/R02 R01/R02 R01/R02 R01/R02 [g/m 2 ] 0.796/0.929 0.796/0.929 0.796/0.929 0.796/0.929 0.796/0.929 0.796/0.929 0.796/0.929 0.796/0.929 0.796/0.929 0.796/0.929 0.796/0.929 0.796/0.929 0.796/0.929 0.796/0.929 0.796/0.929 0.796/0.929 0.796/0.929 0.796/0.929 0.796/0.929 0.796/0.929 0.796/0.929 0.796/0.929 0.796/0.929 BR 18 [g/m 2 ] 6.32 6.32
  • the degree of hardening was determined by allowing a drop of 2-butanone to be absorbed by the thermosensitive element, then wiping the film to remove softening areas and finally uniformly heating the thermographic recording material. Insufficient hardening is shown by regions of the thermographic recording material exhibiting no development due to the softening and removal of the binder containing the silver behenate. The results were evaluated by a visual evaluation:
  • 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 EXAMPLE 1 and INVENTION EXAMPLES 1 to 5.
  • 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 EXAMPLE 1 and INVENTION EXAMPLES 1 to 5 are given in table 3.
  • thermographic recording materials of COMPARATIVE EXAMPLE 1 and INVENTION EXAMPLES 1 to 5 was evaluated on the basis of the observed changes in maximum density, ⁇ D max , and the change in the CIELAB a* and b* values at the minimum density.
  • the CIELAB-values were determined by spectrophotometric measurements according to AST M Norm E179-90 in a R(45/0) geometry with evaluation according to ASTM Norm E308-90. The results are summarized in table 3.
  • thermosensitive elements of the substantially light-insensitive black and white monosheet thermographic recording materials of INVENTION EXAMPLES 6 to 11 were produced as described for INVENTION EXAMPLES 1 to 5 and COMPARATIVE EXAMPLE 1 except as given in table 4 below.
  • Invention example 6 Invention example 7 Invention example 8 Invention example 9 Invention example 10 Invention example 11 AgBeh coverage [g/m 2 ] 5.61 5.58 5.74 5.58 5.72 5.85 reducing agent types R01/R02 R04 R01/R04 R01/R04 R01/R04 R01/R04 [g/m 2 ] 0.706/0.824 1.316 0.361/1.083 0.469/0.921 0.599/0.808 0.736/0.689 BR 18 [g/m 2 ] 5.61 5.58 5.74 5.58 5.72 5.85 L75 [g/m 2 ] 0.642 0.639 0.657 0.725 0.654 0.669 DBTDL 0.013 0.013 0.013 0.013 0.013 0.013 0.013 Oil [g/m 2 ] 0.021 0.021 0.022 0.021 0.022 0.022 T01 [g/m 2 ] 0.315 0.313 0.322 0.313 0.321 0.329 S01 [g/m 2 ] 0.139
  • thermographic recording materials with the thermosensitive element and protective layer hardened with a polyisocyanate
  • thermographic recording materials (INVENTION EXAMPLES 7 to 11) whose prints exhibit a significantly steeper sensitometry than an analogous thermographic recording material (INVENTION EXAMPLE 6) using the reducing agent combination R01 and R02.
  • thermosensitive elements of the substantially light-insensitive black and white monosheet thermographic recording materials of INVENTION EXAMPLES 12 to 17 were produced as described for INVENTION EXAMPLES 1 to 5 and COMPARATIVE EXAMPLE 1 except as given in table 6 below.
  • Invention example 12 Invention example 13
  • Invention example 14 Invention example 15
  • Invention example 16 Invention example 17 AgBeh coverage [g/m 2 ] 5.85 5.77 5.93 5.69 5.74 5.80 reducing agent types R01/R02 R06 R01/R06 R01/R06 R01/R06 R01/R06 [g/m 2 ] 0.736/ 0.859 2.481 0.248/ 1.854 0.478/ 1.562 0.602/ 1.347 0.729/ 1.134 BR 18 [g/m 2 ] 5.85 5.77 5.93 5.69 5.74 5.80 L75 [g/m 2 ] 0.669 0.660 0.678 0.651 0.657 0.663 DBTDL 0.013 0.013 0.014 0.013 0.013 0.013 Oil [g/m 2 ] 0.022 0.022 0.023 0.022 0.022 0.022 T01 [g/m 2 ] 0.329 0.324 0.333 0.320 0.322 0.326 S01 [g/m 2 ]
  • thermosensitive elements of the substantially light-insensitive black and white monosheet thermographic recording materials of INVENTION EXAMPLES 18 to 21 were produced as described for INVENTION EXAMPLES 1 to 5 and COMPARATIVE EXAMPLE 1 except as given in table 8 below.
  • Invention example 18 Invention example 19 Invention example 20
  • Invention example 21 AgBeh coverage [g/m 2 ] 6.32 6.32 6.32 6.32 reducing agent types R01/R02 R01/R02 R01/R02 R01/R02 [g/m 2 ] 1.105/0.155 1.105/0.155 1.105/0.155 BR 18 [g/m 2 ] 6.32 6.32 6.32 6.32 polyisocyanate type N75 VL N100 N3300 [g/m 2 ] 1.45 1.45 1.45 1.45 Oil [g/m 2 ] 0.024 0.024 0.024 0.024 0.024 T01 [g/m 2 ] 0.355 0.355 0.355 0.355 S01 [g/m 2 ] 0.156 0.156 0.156 0.156 S02 [g/m 2 ] 0.142 0.142 0.142 0.142 Thermographic evaluation of the substantially light-insensitive black and white monosheet thermographic recording materials of INVENTION EXAMPLES 18 to 21 were carried out as described for INVENTION EXAMPLES
  • thermosensitive elements of the substantially light-insensitive black and white monosheet thermographic recording materials of INVENTION EXAMPLES 21 to 27 were produced in an analogous way to that described for INVENTION EXAMPLES 1 to 5 and COMPARATIVE EXAMPLE 1 except that the thermosensitive element composition was that given below: AgBeh 3.89 [g/m 2 ] R01, reducing agent 0.855 [g/m 2 ] PIOLOFORMTM BR 18 3.89 [g/m 2 ] DESMODURTM N100 0.401 [g/m 2 ] Oil 0.144 [g/m 2 ] TINUVINTM 320 0.15 [g/m 2 ] T01 0.219 [g/m 2 ] S01 0.235 [g/m 2 ] S02 0.085 [g/m 2 ] The thermosensitive element used in the thermographic recording materials of INVENTION EXAMPLES 21 to 27 was then overcoated with different protective layer compositions given in table 10.
  • thermographic recording material of INVENTION EXAMPLE 21 with DESMODURTM N100 in the protective layer was significantly better than those attained with the thermographic recording materials of INVENTION EXAMPLES 22 to 27 with DESMODURTM VL. Furthermore, the amount of DESMODURTM VL used in the protective layers of the thermographic recording materials of INVENTION EXAMPLES 22 to 27 was found to have little influence on the NGV-values observed and increasing the amount of DESMODURTM VL used resulted in significantly less increase in the CIELAB-b* value upon heating for 24 hours at 80°C.

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

Claims (8)

  1. Ein wesentlich lichtunempfindliches thermografisches Schwarzweiß-Einzelbogen-Aufzeichnungsmaterial mit einem Träger und einem wärmeempfindlichen, mit einer Schutzschicht überzogenen Element, wobei das wärmeempfindliche Element ein wesentlich lichtunempfindliches organisches Silbersalz, ein 1,2-Dihydroxybenzol-Derivat in thermischer wirksamer Beziehung dazu und ein erstes Polymer mit aktiven Wasserstoffatomen enthält, wobei zumindest ein Teil dieser Atome mit einem ersten Polyisocyanat aus der Gruppe bestehend aus Hexamethylendiisocyanat, Toluoldiisocyanat, Diphenylmethandiisocyanat, Naphthylendiisocyanat und Triphenylmethan-p,p',p"-trityltriisocyanat reagiert hat und die Schutzschicht keine fluorhaltigen Verbindungen enthält.
  2. Thermografisches Aufzeichnungsmaterial nach Anspruch 1, dadurch gekennzeichnet, daß das 1,2-Dihydroxybenzol-Derivat eine Verbindung der Formel (I) ist :
    Figure 00260001
    in der bedeuten :
    n 0 oder 1,
    R -(C=O)R1, -(C=O)NR1R2, -CN, -SO3R1, -SO2R1, -SOR1, -SO2NR1R2 oder -PO3R1R2,
    R1 ein Wasserstoffatom, eine gegebenenfalls substituierte Alkylgruppe oder eine gegebenenfalls substituierte Arylgruppe,
    R2 ein Wasserstoffatom, eine gegebenenfalls substituierte Alkylgruppe oder eine gegebenenfalls substituierte Arylgruppe, und
    wobei R1 und R2 zusammen die zum Schließen eines Ringes benötigten Atome bedeuten dürfen.
  3. Thermografisches Aufzeichnungsmaterial nach Anspruch 1, dadurch gekennzeichnet, daß das 1,2-Dihydroxybenzol-Derivat aus der Gruppe bestehend aus Ethyl-3,4-dihydroxybenzoat, Butyl-3,4-dihydroxybenzoat, 3,4-Dihydroxybenzonitril, 2,3,4-Trihydroxyacetophenon, 2,3,4-Trihydroxypropionophenon, 2,3,4-Trihydroxybenzaldehyd, 2,3,4-Trihydroxybutyrophenon und 2,3,4-Trihydroxybenzonitril gewählt wird.
  4. Thermografisches Aufzeichnungsmaterial nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß das erste Polymer mit aktiven Wasserstoffatomen aus der Gruppe bestehend aus Polyvinylalkohol, Polyvinylacetalen und proteinartigen Bindemitteln gewählt wird.
  5. Thermografisches Aufzeichnungsmaterial nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß das wesentlich lichtunempfindliche organische Silbersalz ein Silbersalz einer alifatischen Carbonsäure mit zumindest 12 Kohlenstoffatomen ist.
  6. Thermografisches Aufzeichnungsmaterial nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß die Schutzschicht ein zweites Polymer mit aktiven Wasserstoffatomen und ein zweites Polyisocyanat enthält.
  7. Ein durch die nachstehenden schritte gekennzeichnetes Aufzeichnungsverfahren : (i) Anordnen einer Außenschicht eines thermografischen Aufzeichnungsmaterials nach einem der vorstehenden Ansprüche in der Nähe einer Heizquelle, (ii) bildmäßige Beaufschlagung des thermografischen Aufzeichnungsmaterials mit von der Heizquelle gelieferter Wärme zur Herstellung eines Bildes, wobei das Aufzeichnungsmaterial in der Nähe der Heizquelle gehalten wird, und (iii) Entfernen des thermografischen Aufzeichnungsmaterials von der Heizquelle.
  8. Aufzeichnungsverfahren nach Anspruch 7, dadurch gekennzeichnet, daß die Heizquelle ein Dünnfilm-Thermokopf ist.
EP99204003A 1998-11-30 1999-11-24 Thermographisches Schwarz-Weiss-Aufzeichnungsmaterial mit verbessertem Bildton Expired - Lifetime EP1006405B1 (de)

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US6677274B2 (en) 2000-05-25 2004-01-13 Agfa-Gevaert Thermographic recording material with improved image tone
US7297658B2 (en) * 2005-06-24 2007-11-20 Carestream Health, Inc. Direct thermographic materials with crosslinked carrier layer

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WO1995012495A1 (en) * 1993-11-06 1995-05-11 Agfa-Gevaert Naamloze Vennootschap Direct thermal imaging method using a protected heat-sensitive recording material
US5468603A (en) * 1994-11-16 1995-11-21 Minnesota Mining And Manufacturing Company Photothermographic and thermographic elements for use in automated equipment
US5686228A (en) * 1996-07-25 1997-11-11 Imation Corp. Substituted propenitrile compounds as antifoggants for black-and-white photothermographic and thermographic elements

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