EP0685760B1 - Matériau pour l'enregistrement thermosensible - Google Patents

Matériau pour l'enregistrement thermosensible Download PDF

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Publication number
EP0685760B1
EP0685760B1 EP95201165A EP95201165A EP0685760B1 EP 0685760 B1 EP0685760 B1 EP 0685760B1 EP 95201165 A EP95201165 A EP 95201165A EP 95201165 A EP95201165 A EP 95201165A EP 0685760 B1 EP0685760 B1 EP 0685760B1
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Prior art keywords
layer
recording material
heat
sensitive recording
material according
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German (de)
English (en)
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EP0685760A1 (fr
Inventor
Herman C/O Agfa-Gevaert N.V. Uytterhoeven
Leo C/O Agfa-Gevaert N.V. Oelbrandt
Carlo C/O Agfa-Gevaert N.V. Uyttendaele
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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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M2205/00—Printing methods or features related to printing methods; Location or type of the layers
    • B41M2205/04—Direct thermal recording [DTR]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M2205/00—Printing methods or features related to printing methods; Location or type of the layers
    • B41M2205/38—Intermediate layers; Layers between substrate and imaging layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M2205/00—Printing methods or features related to printing methods; Location or type of the layers
    • B41M2205/40—Cover layers; Layers separated from substrate by imaging layer; Protective layers; Layers applied before imaging
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
    • B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers
    • B41M5/32—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers one component being a heavy metal compound, e.g. lead or iron
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
    • B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers
    • B41M5/333—Colour developing components therefor, e.g. acidic compounds
    • B41M5/3333—Non-macromolecular compounds
    • B41M5/3335—Compounds containing phenolic or carboxylic acid groups or metal salts thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
    • B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers
    • B41M5/337—Additives; Binders
    • B41M5/3372—Macromolecular compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
    • B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers
    • B41M5/337—Additives; Binders
    • B41M5/3377—Inorganic compounds, e.g. metal salts of organic acids
    • 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
    • G03C1/04—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with macromolecular additives; with layer-forming substances
    • G03C1/047—Proteins, e.g. gelatine derivatives; Hydrolysis or extraction products of proteins
    • 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
    • G03C1/49872—Aspects relating to non-photosensitive layers, e.g. intermediate protective layers
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/76—Photosensitive materials characterised by the base or auxiliary layers
    • G03C1/7614—Cover layers; Backing layers; Base or auxiliary layers characterised by means for lubricating, for rendering anti-abrasive or for preventing adhesion
    • 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
    • G03C2200/34—Hydroquinone
    • 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
    • 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
    • G03C8/00—Diffusion transfer processes or agents therefor; Photosensitive materials for such processes
    • G03C8/42—Structural details
    • G03C8/50—Peel-apart units, i.e. the image-forming section being separated from the image-receiving section

Definitions

  • the present invention relates to a recording material suited for use in direct thermal imaging.
  • Thermal imaging or thermography is a recording process wherein images are generated by the use of imagewise modulated thermal energy.
  • thermography two approaches are known :
  • Thermal dye transfer printing is a recording method wherein a dye-donor element is used that is provided with a dye layer wherefrom dyed portions or incorporated dyes are transferred onto a contacting receiver element by the application of heat in a pattern normally controlled by electronic information signals.
  • Thermography is concerned with materials which are substantially not photosensitive, but are sensitive to heat or thermosensitive. Imagewise applied heat is sufficient to bring about a visible change in a thermosensitive imaging material.
  • 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.
  • 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.
  • a typical heat-sensitive copy paper includes in the heat-sensitive layer a thermoplastic binder, e.g ethyl cellulose, a water-insoluble silver salt, e.g. silver stearate and an appropriate organic reducing agent, of which 4-methoxy-1-hydroxy-dihydronaphthalene is a representative.
  • a thermoplastic binder e.g ethyl cellulose
  • a water-insoluble silver salt e.g. silver stearate
  • an appropriate organic reducing agent of which 4-methoxy-1-hydroxy-dihydronaphthalene is a representative.
  • a heterocyclic organic toning agent such as phthalazinone is added to the composition of the heat-sensitive layer.
  • Thermo-sensitive copying paper is used in "front-printing” or “back-printing” using infra-red radiation absorbed and transformed into heat in contacting infra-red light absorbing image areas of an original as illustrated in Figures 1 and 2 of US-P 3,074,809.
  • US-P 3,241,997 concerns a heat-sensitive copying material having two separate layers located one on top of the other and carried by a supporting material, the layers having different melting points and being soluble in different solvents, the solvent of one layer being incapable of dissolving the other layer, the layers containing at least two different chemical reagents capable of reacting with each other when at least one of them is in molten form to produce colour, the colour-producing reagents being located in two different layers, whereby each layer contains at least one colour-producing reagent and whereby no one layer contains all of the colour-producing reagents, at least one of the layers and at least one of the colour-producing reagents melting at most at 150 o C.
  • US P 3,795,532 concerns sheet material containing metal soap reactants and adapted for producing a copy of an original in a heat-activated copying process when associated with a coreactant source to form a couple.
  • the coreactant may be provided as a separate coating directly overlying and bonded to the soap layer.
  • a heat-sensitive recording material containing silver behenate and 4-methoxy-1-naphthol as reducing agent in adjacent water-insoluble polymeric binder layers is also described in Example 1 of US-P 3,094,417.
  • thermosensitive recording material of an organic silver salt and hydroxylamine type reductor in thermal working relationship in adjacent layers containing a thermoplastic water-insoluble binder such as ethyl cellulose and after-chlorinated polyvinyl chloride is described already in US-P 4,082,901.
  • a heat-sensitive recording material is used in the form of an electrically resistive ribbon having a multilayered structure in which a carbon-loaded polycarbonate is coated with a thin aluminium film (ref. Progress in Basic Principles of Imaging Systems - Proceedings of the International Congress of Photographic Science GmbH (Cologne), 1986 ed. by Friedrich Granzer and Erik Moisar - Friedr. Vieweg & Sohn - Braunschweig/Wiesbaden, Figure 6. p. 622).
  • Current is injected into the resistive ribbon by electrically addressing a print head electrode contacting the carbon-loaded substrate, thus resulting in highly localized heating of the ribbon beneath the energized electrode.
  • the recording material is image-wise or pattern-wise heated by means of a modulated laser beam.
  • image-wise modulated infra-red laser light is absorbed in the recording layer in infra-red light absorbing substances converting infra-red radiation into the necessary heat for the imaging reaction.
  • the image-wise applied laser light has not necessarily to be infrared light since the power of a laser in the visible light range and even in the ultraviolet region can be thus high that sufficient heat is generated on absorption of the laser light in the recording material.
  • laser which may be a gas laser, gas ion laser, e.g. argon ion laser, solid state laser, e.g. Nd:YAG laser, dye laser or semi-conductor laser.
  • the image signals for modulating the laser beam or current in the micro-resistors of a thermal printhead are obtained directly e.g. from opto-electronic scanning devices or from an intermediary storage means, e.g. magnetic disc or tape or optical disc storage medium, optionally linked to a digital image work station wherein the image information can be processed to satisfy particular needs.
  • an intermediary storage means e.g. magnetic disc or tape or optical disc storage medium
  • a heat-sensitive recording material suited for use in direct thermal imaging, wherein said material is capable of yielding images with maximum density preferably higher than 2.5 and with a gradation sufficiently low for continuous tone reproduction as is needed e.g. in a portrait for an identification document and in the medical diagnostic field wherein images are produced by e.g. radiography, ultrasound or nuclear magnetic resonance (NMR) signals.
  • NMR nuclear magnetic resonance
  • a further object of the present invention is a reduction in the use of ecologically suspect organic solvents in the coating of such heat-sensitive recording materials.
  • a heat-sensitive recording material suited for use in direct thermal imaging comprising:
  • the present invention also provides a method for producing a heat-sensitive recording material, as defined above, characterized in that said layer (1) is coated from a non-aqueous medium and said layer (2) is coated from an aqueous medium.
  • the present invention further includes a recording process wherein a heat-sensitive recording material, as defined above, is image-wise heated.
  • thermographic recording method with improved continuous tone reproduction wherein a heat-sensitive recording material, as defined above, is image-wise heated by means of a thermal head containing a plurality of image-wise electrically energized heating elements.
  • thermo working relationship means here that the reagents responsible for the image formation can come into reactive contact with each other by diffusion of at least one of the reagents under the influence of heat, e.g. by diffusion through said spacer layer.
  • the layer wherein image-wise a metal image is formed on image-wise reducing the substantially light-insensitive metal salt is called furtheron the recording layer or imaging layer.
  • Fig. 1, 2 and 3 represent characteristic sensitometric curves of prints obtained with heat-sensitive "non-invention" and "invention” recording materials. Said characteristic curves were obtained by plotting optical density (D) (logarithmic values) in the ordinate and linearly increasing amounts of exposure heat (rel. H) in the abscissa.
  • grade refers to the slope of a characteristic curve representing the relationship of optical density (D) plotted in the ordinate versus linearly increasing amounts of heat plotted in the abscissa, said different amounts of heat being applied to the thermographic material in neighbouring area analogously to the production of a stepwedge.
  • the linear increase of heat is obtained e.g. by linearly increasing the heating time at different areas of the recording material while keeping constant the heat input (J) per time unit (s).
  • the heating time can be kept constant and the amount of input-heat is increased linearly.
  • ⁇ is the maximum gradient of said characteristic curve, which is normally the gradient between the end of the toe and the beginning of the shoulder of the characteristic curve.
  • the heat-sensitive recording material according to the present invention yields a gradation which is much lower than can be obtained without using the above mentioned layer assemblage.
  • the speed of diffusion the organic reducing agent(s) out of the hydrophilic binder layer (2) is controlled by the intensity of the heating and the adsorption affinity of said agents to the hydrophilic binder giving rise to a larger amount of visually recognizable "grey-levels" in the imaging layer that contains the reducible substantially light-insensitive metal salt.
  • the coating of a relatively thick (dry coating thickness in the range of 2 to 20 ⁇ m) hydrophilic binder layer containing the diffusible reducing agent in a binder/reducing agent weight ratio in the range of 1/1 to 10/1 is particularly favourable for lowering the gradation.
  • the hydrophilic water-soluble binder of the layer containing the therein diffusible organic reducing agent may be any hydrophilic polymeric binder used in the preparation of photographic silver halide emulsion layers, preferably is a protein-type binding agent such as gelatin, casein, collagen, albumin, or gelatin derivative, e.g. acetylated gelatin.
  • a protein-type binding agent such as gelatin, casein, collagen, albumin, or gelatin derivative, e.g. acetylated gelatin.
  • Further suitable water-soluble binding agents are : polyvinyl alcohol, dextran, gum arabic, zein, agar-agar, arrowroot, pectin, carboxymethyl cellulose, hydroxyethyl cellulose, poly(acrylic acid), and polyvinylpyrrolidone.
  • the optionally present spacer layer (3) is a thin (preferably 0.1 ⁇ m to 10 ⁇ m thick) polymeric layer allowing the passage by diffusion of said reducing agent(s).
  • the spacer layer (3) may be a hydrophilic polymeric layer, e.g. made of modified cellulose, e.g. cellulose diacetate, that has been coated free from reducing agent(s) or is a polymeric layer coated from a latex that on drying has some micro-pores allowing the passage of diffusing reducing agent(s).
  • said spacer layer (3) contains a polymeric binder applied from an organic solvent which binder is permeable for the organic reducing agent(s) in molten state.
  • polyhydroxy-benzene reducing agents having at least two hydroxy groups in ortho- or para-position is preferred for obtaining continuous tone images.
  • reducing agents are catecol (pyrocatechol), hydroquinone, 2-methyl hydroquinone, 2-chloro-hydroquinone, 3-(3,4-dihydroxyphenyl) propionic acid, 1,2-dihydroxybenzoic acid, methyl gallate, ethyl gallate, propyl gallate and tannic acid.
  • Another diffusible (very water-soluble) reducing agent is ascorbic acid belonging to the class of the reductones.
  • Diffusible reducing agents that are useful in the recording material of the present invention, and more particularly the polyhydroxy benzene reducing agents having at least two hydroxy groups in ortho or para position and melting point near 100 °C, may be used in combination with other reducing agents operating as auxiliary reducing agents, e.g. sterically hindered phenols, that on heating become reactive partners in the reduction of the substantially light-insensitive silver salt such as silver behenate, or are used in combination with bisphenols as described in US-P 3,547,648.
  • the auxiliary reducing agents may be present in the imaging layer (1) and/or in the hydrophilic polymeric binder layer (2).
  • the film-forming water-insoluble resin binder of the recording layer containing the substantially light-insensitive organic metal salt is preferably a thermoplastic resin or mixture of such resins, wherein the silver salt can be dispersed homogeneously.
  • a thermoplastic resin or mixture of such resins wherein the silver salt can be dispersed homogeneously.
  • all kinds of natural, modified natural or synthetic water-insoluble resins may be used, e.g. cellulose derivatives such as ethylcellulose, cellulose esters, e.g.
  • cellulose nitrate polymers derived from ⁇ , ⁇ -ethylenically unsaturated compounds such as polyvinyl chloride, after-chlorinated polyvinyl chloride, copolymers of vinyl chloride and vinylidene chloride, copolymers of vinyl chloride and vinyl acetate, polyvinyl acetate and partially hydrolyzed polyvinyl acetate, polyvinyl acetals that are made from polyvinyl alcohol as starting material in which only a part of the repeating vinyl alcohol units may have reacted with an aldehyde, preferably polyvinyl butyral, copolymers of acrylonitrile and acrylamide, polyacrylic acid esters, polymethacrylic acid esters and polyethylene or mixtures thereof.
  • aldehyde preferably polyvinyl butyral
  • copolymers of acrylonitrile and acrylamide polyacrylic acid esters, polymethacrylic acid esters and polyethylene or mixtures thereof.
  • a particularly suitable polyvinyl butyral containing a minor amount of vinyl alcohol units is marketed under the trade name BUTVAR B79 of Monsanto USA and provides a good adherence to hydrophilic water-soluble polymeric layers.
  • the above mentioned polymers or mixtures thereof forming the water-insoluble binder 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 solid state in the recording layer at temperatures below 50 °C but becomes a plasticizer for the recording layer in the heated region and/or liquid solvent for at least one of the redox-reactants, e.g. the reducing agent for the organic silver salt, at a temperature above 60 °C.
  • redox-reactants e.g. the reducing agent for the organic silver salt
  • the layer containing the organic metal salt is commonly coated from an organic solvent containing the binder in dissolved form.
  • the binder to organic metal 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 5 to 20 ⁇ m.
  • Substantially light-insensitive organic silver salts particularly suited for use in a heat-sensitive recording material according to 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, e.g. silver laurate, silver palmitate, silver stearate, silver hydroxystearate, silver oleate and silver behenate, which silver salts are also called "silver soaps”.
  • Modified aliphatic carboxylic acids with thioether group as described e.g. in GB-P 1,111,492 and other organic silver salts as described in GB-P 1,439,478, e.g.
  • silver benzoate and silver phthalazinone may be used likewise to produce a thermally developable silver image.
  • the silver image density depends on the coverage of the above defined reducing agent(s) and organic silver salt(s) and has to be preferably such that, on heating above 100 °C, an optical density of at least 2.5 can be obtained.
  • Useful substantially light-insensitive organic metal salts other than silver salts are e.g. iron salts of an organic acid, e.g. the iron salts described in published European patent application 0 520 404, more particularly iron o-benzoylbenzoate.
  • the recording layer contains preferably in admixture with said organic silver salts and reducing agents a so-called toning agent known from thermography or photo-thermography.
  • 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 within the scope of following general formula : in which : X represents O or N-alkyl; each of R 1 , R 2 , R 3 and R 4 (same or different) represents hydrogen, alkyl, e.g.
  • C1-C20 alkyl preferably C1-C4 alkyl, cycloalkyl, e.g. cyclopentyl or cyclohexyl, alkoxy, preferably methoxy or ethoxy, alkylthio with preferably up to 2 carbon atoms, hydroxy, dialkylamino of which the alkyl groups have preferably up to 2 carbon atoms or halogen, preferably chlorine or bromine; or R 1 and R 2 or R 2 and R 3 represent the ring members required to complete a fused aromatic ring, preferably a benzene ring, or R 3 and R 4 represent the ring members required to complete a fused aromatic aromatic or cyclohexane ring. Toners within the scope of said general formula are described in GB-P 1,439,478 and US-P 3,951,660.
  • a toner compound particularly suited for use in combination with polyhydroxy benzene reducing agents is 3,4-dihydro-2,4-dioxo-1,3,2H-benzoxazine described in US-P 3,951,660.
  • the recording layer may contain other additives such as free fatty acids, surface-active agents, antistatic agents, e.g. non-ionic antistatic agents including a fluorocarbon group as e.g. in F 3 C(CF 2 ) 6 CONH(CH 2 CH 2 O)-H, silicone oil, e.g. BAYSILONE ⁇ l A (tradename of BAYER AG - GERMANY), ultraviolet light absorbing compounds, white light reflecting and/or ultraviolet radiation reflecting pigments, colloidal 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. BAYSILONE ⁇ l A (tradename of BAYER AG - GERMANY)
  • ultraviolet light absorbing compounds e.g. BAYSILONE ⁇ l A (tradename of BAYER AG - GERMANY
  • the support for the heat-sensitive recording material according to the present invention 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 need be to improve the adherence to the thereon coated heat-sensitive recording layer.
  • the coating of the layers (1) and (2) may proceed by any coating technique e.g. 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.
  • Direct thermal imaging can be used for both the production of transparencies and reflection type prints.
  • the support may be transparent or opaque, e.g. the support has a white light reflecting aspect.
  • a paper base is used which may contain white light reflecting pigments, optionally also applied in an interlayer between the recording layer and said base.
  • said base may be colourless or coloured, e.g. has a blue colour.
  • the recording materials of the present invention are particularly suited for use in thermographic recording techniques operating with thermal print-heads.
  • Suitable thermal printing heads are e.g. a Fujitsu Thermal Head (FTP-040 MCS001), a TDK Thermal Head F415 HH7-1089, and a Rohm Thermal Head KE 2008-F3.
  • the hydrophilic binder layer (2) containing the reducing agent(s) is covered with the recording layer (1).
  • Said embodiment is suited for use in by laser induced heat-recording wherein image-wise modulated laser light is directed through a transparent support and heats said layer (2) internally by absorption of the laser light therein.
  • said layer (2) contains preferably infra-red light absorbing substances, examples of which are given in US-P 4,912,083, 5,219,703 and 5,256,620.
  • the imagewise heating of the recording material with said printheads proceeds through a contacting but removable resin sheet or web wherefrom during said heating no transfer of imaging material can take place.
  • the layer (2) containing at least one reducing agent when being the outermost layer may contain hydrophilic finely divided (colloidal) optically transparent inert inorganic pigments such as transparent colloidal silica not masking the lateron formed silver image.
  • the recording material still being capable of obtaining an increase in optical density in the area that were not heated imagewise is stabilized against further density-increasing heat by removing the reductor source, viz. the layer (2) (in case it is a top layer).
  • the removal of said layer may proceed by wash-off with an aqueous liquid, optionally while applying mild rubbing, or by stripping, e.g. using an adhesive sheet or web material firstly laminated to said layer and thereupon peeling apart (stripping off) therewith said layer (2) from the recording layer or spacer layer.
  • the layers (1) or (2) when being a top layer are coated with a protective coating or substances having anti-sticking properties through the presence of (a) lubricating agent(s).
  • the outermost layer of the heat-sensitive recording material according to the present invention may comprise a dissolved lubricating material and/or a dispersed particulate lubricating 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.
  • the surface active agents may be any agents known in the art such as carboxylates, sulfonates, phosphates, aliphatic amine salts, aliphatic quaternary ammonium salts, polyoxyethylene alkyl ethers, polyethylene glycol fatty acid esters, fluoroalkyl C 2 -C 20 aliphatic acids.
  • Examples of liquid lubricants include silicone oils, synthetic oils, saturated hydrocarbons and glycols.
  • solid organic lubricants include various higher alcohols such as stearyl alcohol, fatty acids and fatty acid esters.
  • outermost slipping layers are mentioned layers made from a styrene-acrylonitrile copolymer or a styrene-acrylonitrile-butadiene copolymer or binder mixture hereof containing as lubricant in an amount of 0.1 to 10 % by weight with respect to said binder(s) a polysiloxane-polyether copolymer or polytetrafluoroethylene or a mixture hereof.
  • Another suitable outermost slipping layer may be obtained by coating a solution of at least one silicon compound and a substance capable of forming during the coating procedure a polymer having an inorganic backbone which is an oxide of a group IVa or IVb element as described in published European patent application 0554576.
  • a subbed polyethylene terephthalate support having a thickness of 175 ⁇ m was doctor blade-coated from a coating composition containing methyl ethyl ketone as a solvent and the following ingredients so as to obtain thereon after drying a layer containing per m 2 : silver behenate 4.42 g/m 2 polyvinyl butyral (BUTVAR B79-tradename) 4.42 g/m 2 3,4-dihydro-2,4-dioxo-1,3,2H-benzoxazine 0.34 g/m 2
  • a second layer was coated from a coating composition containing methyl ethyl ketone as a solvent and the following ingredients so as to obtain thereon after drying a layer containing per m 2 : catechol 2.5 g/m 2 copolycarbonate PC3 as identified furtheron 10.0 g/m 2 TEGO-GLIDE 410 (trademark) as identified furtheron 0.5 g/m 2
  • the viscosity ratio is by definition the quotient of the viscosity of the polymer solution and of the pure solvent measured at the same temperature, here 20 °C.
  • TEGO-GLIDE 410 (trademark) is a lubricant of the polysiloxane/polyether type and commercially available from TEGO-CHEMIE.
  • a subbed polyethylene terephthalate support having a thickness of 100 ⁇ m was doctor blade-coated from a coating composition containing methyl ethyl ketone as a solvent and the following ingredients so as to obtain thereon after drying a layer containing per m 2 : silver behenate 7.46 g/m 2 polyvinyl butyral (BUTVAR B79-tradename) 3.73 g/m 2 3,4-dihydro-2,4-dioxo-1,3,2H-benzoxazine 0.85 g/m 2 hydroquinone 0.84 g/m 2
  • a subbed polyethylene terephthalate support having a thickness of 100 ⁇ m was doctor blade-coated from a coating composition containing methyl ethyl ketone as a solvent and the following ingredients so as to obtain thereon after drying a first layer containing per m 2 : silver behenate 7.46 g/m 2 polyvinyl butyral (BUTVAR B79-tradename) 3.73 g/m 2 3,4-dihydro-2,4-dioxo-1,3,2H-benzoxazine 0.85 g/m 2
  • a second layer was coated from aqueous medium so as to obtain thereon after drying a hydrophilic polymeric binder layer containing : hydroquinone 0.84 g/m 2 gelatin 1.00 g/m 2
  • the heat-sensitive recording materials A1, B1 and that of comparative example 1 were exposed to a pattern of linearly increasing amounts of heat in a thermal head printer built for thermosensitometric purposes, using a separable polyethylene terephthalate ribbon of 6 ⁇ m thickness between the thermal print head and the outermost non-support layer of the heat-sensitive recording materials.
  • the optical density was measured in transmission with Macbeth TD 904 densitometer behind ortho-filter having its main transmission in the green part (500 nm to 600 nm) of the visible spectrum.
  • sensitometric curve B1 corresponding with the invention material B1 is considerably less steep than the slope of curve A1, and proves a soft gradation characteristic allowing the reproduction of at least 40 increasing grey values, whereas the non-invention material A1 may yield only 20 recognizable steps.
  • a subbed polyethylene terephthalate support having a thickness of 100 ⁇ m was doctor blade-coated from a coating composition containing methyl ethyl ketone as a solvent and the following ingredients so as to obtain thereon after drying a layer containing per m 2 : silver behenate 7.46 g/m 2 polyvinyl butyral (BUTVAR B79-tradename) 3.73 g/m 2 3,4-dihydro-2,4-dioxo-1,3,2H-benzoxazine 0.85 g/m 2 catechol 0.84 g/m 2
  • a subbed polyethylene terephthalate support having a thickness of 100 ⁇ m was doctor blade-coated from a coating composition containing methyl ethyl ketone as a solvent and the following ingredients so as to obtain thereon after drying a first layer containing per m 2 : silver behenate 7.46 g/m 2 polyvinyl butyral (BUTVAR B79-tradename) 3.73 g/m 2 3,4-dihydro-2,4-dioxo-1,3,2H-benzoxazine 0.85 g/m 2
  • a second layer was coated from aqueous medium so as to obtain thereon after drying a hydrophilic polymeric binder layer containing : catechol 0.84 g/m 2 gelatin 2.10 g/m 2
  • the preparation of recording material C2 was the same as of recording material B2 with the difference however, that the coverage of catechol in the second layer was 1.26 g/m 2 and the coverage of gelatin 4.20 g/m 2 .
  • the preparation of recording material D2 was the same as of recording material C2 with the difference however, that the coverage of gelatin in the second layer was doubled, viz. 8.40 g/m 2 .
  • the heat-sensitive recording materials A2, B2, C2 and D2 were exposed to a pattern of linearly increasing amounts of heat in a thermal head printer built for thermosensitometric purposes, using a separable polyethylene terephthalate ribbon of 6 ⁇ m thickness between the thermal print head and the outermost non-support layer of the heat-sensitive recording materials.
  • the optical density was measured in transmission with Macbeth TD 904 densitometer behind ortho-filter having its main transmission in the green part (500 nm to 600 nm) of the visible spectrum.
  • sensitometric curves B2, C2 and D2 corresponding with the invention materials B2, C2 and D2 respectively is much less steep than the slope of curve A2. From the obtained sensitometric results it may be concluded that by coating from an aqueous medium a proper combination of hydrophilic binding agent (gelatin) and reducing agent in a hydrophilic binder layer adjacent to the imaging layer a soft gradation together with a high optical density can be obtained.
  • hydrophilic binding agent gelatin
  • a subbed polyethylene terephthalate support having a thickness of 100 ⁇ m was doctor blade-coated from a coating composition containing methyl ethyl ketone as a solvent and the following ingredients so as to obtain thereon after drying a layer containing per m 2 : silver behenate 7.46 g/m 2 polyvinyl butyral (BUTVAR B79-tradename) 3.73 g/m 2 3,4-dihydro-2,4-dioxo-1,3,2H-benzoxazine 0.85 g/m 2 catechol 0.84 g/m 2
  • a subbed polyethylene terephthalate support having a thickness of 100 ⁇ m was doctor blade-coated from a coating composition containing methyl ethyl ketone as a solvent and the following ingredients so as to obtain thereon after drying a first layer containing per m 2 : silver behenate 7.46 g/m 2 polyvinyl butyral (BUTVAR B79-tradename) 3.73 g/m 2 3,4-dihydro-2,4-dioxo-1,3,2H-benzoxazine 0.85 g/m 2
  • a second layer was coated from aqueous medium so as to obtain thereon after drying a hydrophilic polymeric binder layer containing : hydroquinone 0.84 g/m 2 gelatin 2.10 g/m 2
  • a subbed polyethylene terephthalate support having a thickness of 100 ⁇ m was doctor blade-coated from a coating composition containing methyl ethyl ketone as a solvent and the following ingredients so as to obtain thereon after drying a first layer containing per m 2 : silver behenate 7.46 g/m 2 polyvinyl butyral (BUTVAR B79-tradename) 3.73 g/m 2 3,4-dihydro-2,4-dioxo-1,3,2H-benzoxazine 0.85 g/m 2
  • a second layer serving as spacer layer was coated from methyl ethyl ketone so as to obtain thereon after drying a layer containing : copolycarbonate PC3 as identified above 5.00 g/m 2
  • hydrophilic polymeric binder/reductor composition Onto said dried spacer layer a hydrophilic polymeric binder/reductor composition was coated from aqueous medium so as to obtain thereon after drying a hydrophilic polymeric binder layer containing : catechol 0.84 g/m 2 gelatin 2.10 g/m 2
  • the heat-sensitive recording materials A3, B3 and C3 were exposed to a pattern of linearly increasing amounts of heat in a thermal head printer built for thermosensitometric purposes, using a separable polyethylene terephthalate ribbon of 6 ⁇ m thickness between the thermal print head and the outermost non-support layer of the heat-sensitive recording materials.
  • the optical density was measured in transmission with Macbeth TD 904 densitometer behind ortho-filter having its main transmission in the green part (500 nm to 600 nm) of the visible spectrum.
  • the slope of the linear part (between toe and shoulder) of sensitometric curves B3 and C3 corresponding with the invention materials B3 and C3 respectively is considerably less steep than the slope of curve A3, and proves a soft gradation characteristic suited for continuous tone reproduction.
  • the C3 invention recording material allows the reproduction of at least 48 increasing grey values, whereas the non-invention material A3 may yield only 20 recognizable steps.
  • a subbed polyethylene terephthalate support having a thickness of 100 ⁇ m was doctor blade-coated from a coating composition containing methyl ethyl ketone as a solvent and the following ingredients so as to obtain thereon after drying a layer containing per m 2 : silver behenate 6.00 g/m 2 polyvinyl butyral (BUTVAR B79-tradename) 3.00 g/m 2 3,4-dihydro-2,4-dioxo-1,3,2H-benzoxazine 0.22 g/m 2 behenic acid 0.60 g/m 2 BAYSILONE ⁇ l A (tradename) 17 mg/m 2
  • a second layer was coated from acetone so as to obtain thereon after drying a spacer layer containing : cellulose diacetate 7.00 g/m 2
  • the heat-sensitive recording material A4 was exposed to a pattern of linearly increasing amounts of heat in a thermal head printer built for thermosensitometric purposes, using a separable polyethylene terephthalate ribbon of 6 ⁇ m thickness between the thermal print head and the outermost non-support layer of the heat-sensitive recording material.
  • the optical density was measured in transmission with Macbeth TD 904 densitometer behind ortho-filter having its main transmission in the green part (500 nm to 600 nm) of the visible spectrum.
  • the measured optical density was more than 3 in the stronger heat-exposed area. In the non-exposed area the optical density was 0.06.
  • the two upper layers (second and third layer) of the recording material A4 were removed by stripping off using an adhesive tape.
  • the remaining material including the imaging layer (first layer) was overall heated at a temperature of 118 °C for 5 seconds.
  • optical density was repeated and the recording material after said stripping off and overall heating possessed an optical density of 0.04 in the previously non-heated areas whereas the optical density remained practically the same in the previously image-wise heated areas.

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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 (16)

  1. Un matériau d'enregistrement thermosensible approprié à être utilisé dans l'imagerie thermique directe, lequel matériau d'enregistrement comprend:
    (i) une couche (1) contenant, distribué de manière uniforme dans un liant de résine filmogène et insoluble dans l'eau, un sel métallique organique essentiellement insensible à la lumière, et
    (ii) une couche (2) en contact direct avec ladite couche (1) ou dans une relation thermiquement opérante avec celle-ci à travers l'intermédiaire d'une couche d'espacement (3), caractérisé en ce que ladite couche (2) contient, distribué de manière uniforme dans un liant hydrophile filmogène et soluble dans l'eau, un réducteur organique qui soit capable de diffuser à partir de la couche (2) dans la couche (1) lors de l'échauffement dudit matériau d'enregistrement.
  2. Matériau d'enregistrement thermosensible selon la revendication 1, caractérisé en ce que ledit sel métallique organique est un sel d'argent.
  3. Matériau d'enregistrement thermosensible selon la revendication 1 ou 2, caractérisé en ce que ledit liant hydrophile hydrosoluble est un liant de type protéinique, de l'alcool polyvinylique, du poly(acide acrylique) ou de la polyvinylpyrrolidone.
  4. Matériau d'enregistrement thermosensible selon la revendication 3, caractérisé en ce que ce liant hydrophile hydrosoluble est de la gélatine.
  5. Matériau d'enregistrement thermosensible selon l'une quelconque des revendications 1 à 4, caractérisé en ce que ladite couche (2) contient ledit (lesdits) réducteur(s) dans un rapport pondéral liant/réducteur entre 1/1 et 10/1.
  6. Matériau d'enregistrement thermosensible selon l'une quelconque des revendications 1 à 5, caractérisé en ce que ladite couche (2) contient un réducteur de polyhydroxybenzène.
  7. Matériau d'enregistrement thermosensible selon la revendication 6, caractérisé en ce que ledit réducteur de polyhydroxybenzène est le catéchol ou l'hydroquinone.
  8. Matériau d'enregistrement thermosensible selon l'une quelconque des revendications précédentes, caractérisé en ce que ladite couche (2) est une couche extérieure ou ladite couche (1) est une couche extérieure.
  9. Matériau d'enregistrement thermosensible selon l'une quelconque des revendications 1 à 7, caractérisé en ce que ladite couche (1) ou (2) est enduite d'une couche protectrice extérieure possédant des caractéristiques anti-adhésives grâce à la présence d'une substance lubrifiante là-dedans.
  10. Matériau d'enregistrement thermosensible selon l'une quelconque des revendications précédentes, caractérisé en ce que ce matériau d'enregistrement contient un support opaque ou transparent.
  11. Matériau d'enregistrement thermosensible selon l'une quelconque des revendications précédentes, caractérisé en ce que ladite couche (2) est coulée sur un support transparent, que la couche (1) est située au-dessus d'elle et qu'elle contient des substances absorbant la lumière laser qui convertissent la lumière laser absorbée en chaleur.
  12. Une méthode pour faire le matériau d'enregistrement thermosensible tel que défini dans l'une quelconque des revendications précédentes, caractérisée en ce que ladite couche (1) est coulée à partir d'un milieu non aqueux et que ladite couche (2) est coulée à partir d'un milieu aqueux.
  13. Un procédé d'enregistrement impliquant l'échauffement en forme d'image d'un matériau d'enregistrement tel que défini dans l'une quelconque des revendications 1 à 11.
  14. Procédé d'enregistrement selon la revendication 13, caractérisé en ce que le matériau d'enregistrement thermosensible est échauffé en forme d'image au moyen d'une tête thermique contenant une pluralité d'élément chauffants activés électriquement en forme d'image.
  15. Procédé d'enregistrement selon l'une quelconque des revendications 13 et 14, caractérisé en ce que ladite couche (2) est enlevée après l'échauffement en forme d'image.
  16. Procédé d'enregistrement selon la revendication 15, caractérisé en ce que ladite couche (2) est enlevée par lavage avec un liquide aqueux ou par délamination.
EP95201165A 1994-05-30 1995-05-08 Matériau pour l'enregistrement thermosensible Expired - Lifetime EP0685760B1 (fr)

Priority Applications (1)

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EP95201165A EP0685760B1 (fr) 1994-05-30 1995-05-08 Matériau pour l'enregistrement thermosensible

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Application Number Priority Date Filing Date Title
EP94201525 1994-05-30
EP94201525 1994-05-30
EP95201165A EP0685760B1 (fr) 1994-05-30 1995-05-08 Matériau pour l'enregistrement thermosensible

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EP0685760B1 true EP0685760B1 (fr) 2000-03-29

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Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3241997A (en) * 1961-12-23 1966-03-22 Schutzner Walter Heat-sensitive copying material
US3795532A (en) * 1971-03-10 1974-04-05 Minnesota Mining & Mfg Wide latitude copy sheet
AU568350B2 (en) * 1983-04-11 1987-12-24 Teesport Ltd. Heat sensitive color producing coating composition
JP3176941B2 (ja) * 1990-12-17 2001-06-18 株式会社リコー 感熱記録材料
EP0599369B1 (fr) * 1992-11-16 1997-02-19 Agfa-Gevaert N.V. Matériau d'enregistrement thermosensible

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