EP0614770B1 - Beschützendes wärmeempfindliches Aufzeichnungsmaterial - Google Patents

Beschützendes wärmeempfindliches Aufzeichnungsmaterial Download PDF

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Publication number
EP0614770B1
EP0614770B1 EP94200473A EP94200473A EP0614770B1 EP 0614770 B1 EP0614770 B1 EP 0614770B1 EP 94200473 A EP94200473 A EP 94200473A EP 94200473 A EP94200473 A EP 94200473A EP 0614770 B1 EP0614770 B1 EP 0614770B1
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EP
European Patent Office
Prior art keywords
recording material
thermosensitive recording
layer
silver salt
cellulose nitrate
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EP94200473A
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English (en)
French (fr)
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EP0614770A1 (de
Inventor
Carlo C/O Agfa-Gevaert N.V. Uyttendaele
Herman C/O Agfa-Gevaert N.V. Uytterhoeven
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Agfa Gevaert NV
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Agfa Gevaert NV
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Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/494—Silver salt compositions other than silver halide emulsions; Photothermographic systems ; Thermographic systems using noble metal compounds
    • G03C1/498—Photothermographic systems, e.g. dry silver
    • G03C1/4989—Photothermographic systems, e.g. dry silver characterised by a thermal imaging step, with or without exposure to light, e.g. with a thermal head, using a laser
    • 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
    • B41M5/40—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used characterised by the base backcoat, intermediate, or covering layers, e.g. for thermal transfer dye-donor or dye-receiver sheets; Heat, radiation filtering or absorbing means or layers; combined with other image registration layers or compositions; Special originals for reproduction by thermography
    • B41M5/42—Intermediate, backcoat, or covering layers
    • B41M5/44—Intermediate, backcoat, or covering layers characterised by the macromolecular compounds
    • 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
    • B41M2205/40—Cover layers; Layers separated from substrate by imaging layer; Protective layers; Layers applied before imaging
    • 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
    • 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
    • G03C2001/7635—Protective layer

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 dye is 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.
  • 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 3,107,174 discloses a copy-sheet structure with a protective layer, a silver soap, reducing agent, toners and other auxiliary components, together with a terpene resin and zinc oxide, uniformly intimately dispersed within a resinous binder as a coating on a paper or paper-like carrier and the protective surface coating being applied over the color-forming coating.
  • a protective layer is opaque, a transparent or paper is employed as the carrier member.
  • 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 the 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.
  • thermosensitive copying papers including a recording layer having a substantially light-insensitive organic silver salt and organic reducing agent in a thermoplastic binder such as polyvinyl acetate and polyvinyl butyral (ref. Re 30,107 being reissue of US-P 3,996,397).
  • a thermoplastic binder such as polyvinyl acetate and polyvinyl butyral (ref. Re 30,107 being reissue of US-P 3,996,397).
  • Such recording materials are less suited for use in thermographic recording operating with thermal printheads since these recording layers may stick thereto.
  • organic ingredients of the thermosensitive recording layer may exude by heat and may soil the thermal printhead at an operating temperature in the range of 300 to 400 °C which are temperatures common in using thermal printheads (ref.the above mentioned book "Handbook of Imaging Materials", p. 502).
  • the undesirable transfer of said ingredients may be promoted by the pressure contact of the thermal printhead with the recording material.
  • Pressures may be 200-500 g/cm 2 to ensure a good transfer of heating.
  • the heating time per picture element (pixel) may be less than 1.0 ms.
  • thermosensitive recording material suited for use in direct thermal imaging, wherein the thermosensitive imaging layer of said material is effectively protected without substantial loss in imaging properties such as sensitivity and image resolution.
  • thermosensitive recording material suited for use in direct thermal imaging, wherein the thermosensitive imaging layer of said material is coated with a protective layer that when contacted with an imagewise energized heating element does not stick thereto and prevents soiling of the heating element.
  • thermosensitive recording material suited for use in direct thermal imaging by means of an information-wise energized heating element
  • recording material comprises on the same side of a support, called the heat-sensitive side, one or more layers containing in thermal working relationship one or more substances yielding an optical density change by heat, characterized in that one of said layers is coated with a protective transparent layer essentially consisting of a cellulose nitrate having a substitution degree (DS) in the range of 2.2 to 2.32, which corresponds with a nitrogen content of 11.8 to 12.2 % by weight, and optionally in addition to said cellulose nitrate a polymer increasing the glass transition temperature above the glass temperature of said cellulose nitrate, a plasticizer and/or a liquid lubricant.
  • DS substitution degree
  • the present invention includes also the use of said recording material in a direct thermal imaging method wherein said method comprises the step of heating the thermosensitive recording layer of said thermosensitive recording material via said protective layer.
  • thermo working relationship is meant here that said substances may be present in a same layer or different layers wherefrom by heat they can come into reactive contact with each other, e.g. by diffusion or mixing in the melt.
  • the layer in which the optical density change takes place is called the recording layer.
  • the cellulose nitrate for forming a protective layer according to the present invention may be applied from methanol, ethanol, ethyl, butyl and amyl acetates, acetone and methyl ethyl ketone or mixtures thereof.
  • the cellulose nitrate coating is preferably applied from a solution in methanol which is a non-solvent for polyvinyl butyral being a preferred binder for organic reducible silver salts.
  • a cellulose nitrate suitable for use as protective surface coating is the following :
  • n is related to the viscosity in a given solvent which for a cellulose nitrate preferred for use according to the present invention is at least 50 mPa.s when measured at 20 °C in methanol at a concentration of 7 g/100 ml.
  • Cellulose nitrate having a value of n in the range of 500 to 600 is used advantageously for the purpose of the present invention and has been described for use as automotive lacquer [ref. The Chemistry of Organic Film Formers by D. H. Solomon - John Wiley & Sons, Inc. New York (1967), p. 151].
  • Cellulose nitrate may be mixed with polymer(s) providing a mixture having a glass transition temperature (Tg) above that of the applied cellulose nitrate, e.g. is mixed with poly(methacrylates) which are compatible therewith.
  • Tg glass transition temperature
  • the cellulose nitrate protective layer used according to the present invention may contain additives provided such materials do not inhibit its anti-sticking properties and provided that such materials do not scratch, erode, contaminate, or otherwise damage the thermal printing head or harm image quality.
  • suitable additives are e.g. plasticizers to improve flexibility.
  • Preferred for that purpose are the simple or polymeric esters of aliphatic or aromatic acids, e.g. of sebacates and adipates.
  • Drying-oil alkyd resins impart greater film strength and resistance to embrittlement.
  • Antioxidants must be added to the drying oil alkyds to prevent cross-linking and partial solubility in the solvents for coating the cellulose nitrate.
  • the protective layer of the direct thermal recording material according to the present invention may in addition to the inorganic silicate particles comprise or is coated with minor amounts of such other agents like liquid lubricants.
  • suitable lubricating materials are surface active agents with or without a polymeric binder.
  • a surface active agent is an amphiphilic molecule containing an apolar group in conjunction with (a) polar group(s) such as carboxylate, sulfonate, phosphates, aliphatic amine salt, aliphatic quaternary ammonium salt groups, polyoxyethylene alkyl ethers, polyethylene glycol fatty acid esters, and fluoroalkyl C 2 -C 20 aliphatic acids.
  • polar group(s) such as carboxylate, sulfonate, phosphates, aliphatic amine salt, aliphatic quaternary ammonium salt groups, polyoxyethylene alkyl ethers, polyethylene glycol fatty acid esters, and fluoroalkyl C 2 -C 20 aliphatic acids.
  • liquid lubricants include silicone oils, synthetic oils, saturated hydrocarbons and glycols.
  • Siloxane compounds may be applied as a topcoat on the protective layer, preferably are coated in the form of a solution in a non-solvent for the cellulose nitrate e.g. from isopropanol or a C 6 -C 11 alkane.
  • the protective layer has preferably a thickness of about 0.1 to 3 ⁇ m, more preferably of 0.3 to 1.5 ⁇ m, and may be coated on the thermosensitive recording layer by a coating technique known as a gravure printing.
  • the protective layer according to the present invention is coated with an outermost slipping layer (i.e. anti-sticking layer) compositions of which are described in e.g. EP 138483, EP 227090, US-P 4,567,113, 4,572,860 and 4,717,711 and in published European patent application 311841.
  • an outermost slipping layer i.e. anti-sticking layer
  • a suitable slipping layer comprises as binder a styrene-acrylonitrile copolymer or a styrene-acrylonitrile-butadiene copolymer or a mixture hereof and as lubricant in an amount of 0.1 to 10 % by weight of the binder(s) a polysiloxane-polyether copolymer or polytetrafluoroethylene or a mixture hereof.
  • Another suitable 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 slipping layer may have a thickness of about 0.2 to 5.0 ⁇ m, preferably in the range of 0.4 to 2.0 ⁇ m.
  • thermographic recording material for direct thermal recording having a recording layer protected with said cellulose nitrate-containing layer as described herein may be of any type known in the art.
  • thermosensitive recording layer containing substantially light-insensitive organic silver salts in admixture with a reducing agent therefor in a water-insoluble resin binder are used.
  • the reducing agent present may be of the type used in known thermographic recording materials for producing a silver image by thermally initiated reduction of substantially light-insensitive silver salts such as silver behenate. Examples of such reducing agents are described in US-P 3,887,378 and prior art mentioned therein and also in Re. 30,107 being reissue of US patent 3,996,397.
  • Sterically hindered phenols or bis-phenols may be used as auxiliary reducing agents that become on heating reactive partners in the reduction of a light-insensitive silver salt such as silver behenate.
  • Substantially light-insensitive organic silver salts particularly suited for use in direct thermal recording materials according to the present invention are silver salts of aliphatic carboxylic acids known as fatty acids, wherein the aliphatic carbon chain has at least 12 C-atoms, e.g. silver palmitate, silver stearate and silver behenate, but modified aliphatic carboxylic acids with thioether group as described e.g. in GB-P 1,111,492 may be used likewise to produce a thermally developable silver image.
  • aliphatic carboxylic acids known as fatty acids, wherein the aliphatic carbon chain has at least 12 C-atoms, e.g. silver palmitate, silver stearate and silver behenate
  • modified aliphatic carboxylic acids with thioether group as described e.g. in GB-P 1,111,492 may be used likewise to produce a thermally developable silver image.
  • the silver image density depends on the coverage of the 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 3 can be obtained.
  • Preferably at least 0.10 mole of reducing agent(s) per mole of organic silver salt is used.
  • the fatty acid silver salts are present in combination with the free fatty acids.
  • the ratio by weight of the resin binder to organic silver salt is e.g. in the range of 0.2 to 6, and the thickness of the recording layer is preferably in the range of 3 to 30 ⁇ m, more preferably in the range of 8 to 16 ⁇ m.
  • thermosensitive recording material contains in one layer a substantially light-insensitive silver salt and in another layer in thermal working relationship with said silver salt one or more reducing agents therefor.
  • a heat-sensitive recording material containing silver behenate and 4-methoxy-1-naphthol as reducing agent in adjacent binder layers is described in Example 1 of US-P 3,094,417.
  • the recording layer contains in admixture with said organic silver salt and reducing agent(s) 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 the already mentioned Re. 30,107. Further reference is made to the toning agents described in US-P 3,074,809, 3,446,648 and 3,844,797. Other useful toning agents are benzoxazine dione compounds, e.g. 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 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, 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
  • ultraviolet light absorbing compounds e.g. in F 3 C(CF 2 ) 6 CONH(CH 2 CH 2 O)-H
  • white light reflecting and/or ultraviolet radiation reflecting pigments e.g. in C(CF 2 ) 6 CONH(CH 2 CH 2 O)-H
  • colloidal silica e.g. infrared silica
  • optical brightening agents e.g., ultraviolet light absorbing compounds
  • thermoplastic resins are used wherein the ingredients can be dispersed homogeneously or form therewith a solid-state solution.
  • natural, modified natural or synthetic resins may be used, e.g. cellulose derivatives such as ethylcellulose, cellulose esters, carboxymethylcellulose, starch ethers, galactomannan, polymers derived from ⁇ , ⁇ -ethylenically unsaturated compounds such as polyvinyl chloride, copolymers of vinyl chloride and vinyl acetate, polyvinyl acetate and partially hydrolyzed polyvinyl acetate, polyvinyl alcohol, polyvinyl acetals, e.g.
  • polyvinyl butyral copolymers of acrylonitrile and acrylamide, polyacrylic acid esters, polymethacrylic acid esters and polyethylene.
  • a particularly suitable ecologically interesting (halogen-free) binder is polyvinyl butyral.
  • thermographic recording layer may be used in conjunction with waxes or "heat solvents” also called 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 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
  • Useful for that purpose are a polyethylene glycol having a mean molecular weight in the range of 1,500 to 20,000 described in US-P 3,347,675.
  • the support for the heat-sensitive recording material 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 may be subbed to improve its adherence to the thereon coated thermo-sensitive recording layer.
  • the coating of the recording layer composition may proceed by any coating technique known in the art using a solvent or solvent mixture for the coating ingredients. Common coating techniques are described e.g. 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.
  • Suitable coating techniques are screen-printing, gravure, forward and reverse roll coating. Screen-printing, spray coating and gravure coating are used as a precision method for applying very thin coatings with more accuracy than can be achieved with other techniques.
  • the direct thermal recording material according to the present invention is particularly suited for use in electrically energized thermal printhead recording.
  • the thermal printhead makes contact with the protective coating of the direct thermal recording material.
  • the thermal printhead contains tiny selectively electrically energized resistors that may not be soiled and have to be protected against wear.
  • thermal printheads 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.
  • FTP-040 MCS001 Fujitsu Thermal Head
  • TDK Thermal Head F415 HH7-1089 a TDK Thermal Head F415 HH7-1089
  • Rohm Thermal Head KE 2008-F3 Rohm Thermal Head KE 2008-F3.
  • the information-wise heating may proceed likewise by means of a resistive ribbon wherein an electrical current is injected through tiny printhead electrodes (styli) into a resistive layer (surface resistivity in the range of 500 to 900 ohms/square) coated at the side opposite said electrodes with a continuous electrode, e.g. in the form of vacuum-deposited aluminium layer.
  • a large ground plate electrode aside said printhead electrodes and in contact with the resistive layer ensures that Joule heating is minimized as the current flows to ground (see the already mentioned book "Progress in Basic Principles of Imaging Systems -Proceedings of the International Congress of Photographic Science GmbH (Cologne)", (1986) Figure 6 on page 622 dealing with an embodiment of resistive ribbon printing technology).
  • composition and production of a polycarbonate ribbon for non-impact printing is described e.g. in US-P 4,103,066.
  • the image signals for modulating the electrical energy to be converted into thermal energy in said thermal printhead or resistive ribbon is 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
  • the present recording material is used in conjunction with an information-wise modulated laser beam or ultrasonic pixel printer as described e.g. in US-P 4,908,631.
  • Direct thermal imaging can be used for both the production of transparencies and reflection type prints having an opaque white light reflecting background.
  • white opaque base e.g. paper base
  • Said base and/or a layer between the recording layer may contain white light reflecting pigments.
  • Black-and-white transparencies are widely used in the medical diagnostic field in inspection techniques operating with a light box.
  • a subbed polyethylene terephthalate support having a thickness of 100 ⁇ m was doctor blade-coated so as to obtain thereon after drying the following recording layer including : silver behenate 5.28 g/m 2 polyvinyl butyral 5.34 g/m 2 behenic acid 0.53 g/m 2 reducing agent S as defined hereinafter 2.0 g/m 2 3,4-dihydro-2,4-dioxo-1,3,2H-benzoxazine 0.39 g/m 2 Reducing agent S is a polyhydroxy spiro-bis-indane, viz. 3,3,3',3'-tetramethyl-5,6,5',6'-tetrahydroxy-spiro-bis-indane.
  • said recording layer was dip-coated at a wet coating thickness of 75 g/m 2 with the following coating composition for forming an outermost protective layer.
  • a solution of 7 g of said cellulose nitrate in 100 ml of methanol has a viscosity of 58 mPa.s at 20 °C.
  • the coated layer was dried for 10 minutes at 70 °C.
  • a first sample of the thus obtained recording material was used immediately after said drying in direct thermal recording with thermal printer MITSUBISHI CP100 (tradename); a second sample was used after 3 days conditioning at 57 °C and relative humidity of 34 %, and a third sample was used after 7 days conditioning at 45 °C and relative humidity of 70 %. During printing the printhead was kept in contact with the protective coating.
  • thermosensitive layer The adherence of the protective layer to the thermosensitive layer proved to be excellent for the three samples. Marks (stripes) resulting from sticking to the thermal printhead material surface are practically nil, whereas without said protective layer stripes are clearly visible and thus deteriorating the image.
  • the optical densities of the protected imaged and non-imaged areas were measured in transmission with densitometer MACBETH TD 904 (tradename) provided with an ortho filter (maximal transmission at about 500 nm).
  • the measured minimum optical density (D min ) was 0.05 and the maximum optical density (D max ) was for all three samples above 3.

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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 (6)

  1. Ein wärmeempfindliches Aufzeichnungsmaterial, das sich für den Einsatz bei der direkten thermischen Bilderzeugung unter Verwendung eines informationsmäßig erregten Heizelementes eignet, wobei das Aufzeichnungsmaterial an derselben Seite eines Trägers, die als wärmeempfindliche Seite bezeichnet wird, eine oder mehrere Schichten umfaßt, die in thermisch wirksamer Beziehung eine oder mehrere Substanzen enthalten, die eine Änderung der optischen Dichte durch Wärme ergeben, dadurch gekennzeichnet, daß eine dieser Schichten mit einer durchsichtigen Schutzschicht überzogen ist, die im wesentlichen aus einem Cellulosenitrat mit einem Substitutionsgrad (DS) im Bereich von 2,2 bis 2,32 und wahlweise außer diesem Cellulosenitrat aus einem Polymeren, das der Glasumwandlungspunkt bis über den Glasumwandlungspunkt dieses Cellulosenitrats erhöht, aus einem Weichmacher und/oder einem flüssigen Gleitmittel besteht.
  2. Wärmeempfindliches Aufzeichnungsmaterial nach Anspruch 1, dadurch gekennzeichnet, daß dieses Cellulosenitrat, wenn es in Methanol bei einer Konzentration von 7 g/100 ml aufgelöst wird, bei 20 °C eine Viskosität von wenigstens 50 mPa.s ergibt.
  3. Wärmeempfindliches Aufzeichnungsmaterial nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß es eine wärmeempfindliche Aufzeichnungsschicht umfaßt, die ein im wesentlichen nicht lichtempfindliches organisches Silbersalz unter Beimischung eines Reduktionsmittels dafür in einem wasserunlöslichen Harzbindemittel, enthält
  4. Wärmeempfindliches Aufzeichnungsmaterial nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß eine dieser Schichten ein im wesentlichen nicht lichtempfindliches organisches Silbersalz enthält, und eine andere Schicht ein oder mehrere Reduktionsmittel dafür in thermisch wirksamer Beziehung zu diesem Silbersalz enthält.
  5. Wärmeempfindliches Aufzeichnungsmaterial nach Anspruch 3 oder 4, dadurch gekennzeichnet, daß das Silbersalz ein Silbersalz einer aliphatischen Carbonsäure ist, deren aliphatische Kohlenstoffkette wenigstens 12 C-Atom enthält.
  6. Ein direktes thermisches Bilderzeugungsverfahren, bei dem zusammen mit einem informationsmäßig erregten Heizelement ein wärmeempfindliches Aufzeichnungsmaterial nach irgendeinem der Ansprüche 1 bis 5 verwendet wird, dadurch gekennzeichnet, daß dieses Verfahren den Schritt umfaßt, wobei die wärmeempfindliche Aufzeichnungsschicht dieses Materials über die sich mit dem Heizelement im Kontakt befindliche Schutzschicht erhitzt wird.
EP94200473A 1993-03-08 1994-02-24 Beschützendes wärmeempfindliches Aufzeichnungsmaterial Expired - Lifetime EP0614770B1 (de)

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EP94200473A EP0614770B1 (de) 1993-03-08 1994-02-24 Beschützendes wärmeempfindliches Aufzeichnungsmaterial

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
EP93200652 1993-03-08
EP93200652 1993-03-08
EP94200473A EP0614770B1 (de) 1993-03-08 1994-02-24 Beschützendes wärmeempfindliches Aufzeichnungsmaterial

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EP0614770A1 EP0614770A1 (de) 1994-09-14
EP0614770B1 true EP0614770B1 (de) 1997-05-07

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EP94200473A Expired - Lifetime EP0614770B1 (de) 1993-03-08 1994-02-24 Beschützendes wärmeempfindliches Aufzeichnungsmaterial

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Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1146078B (de) * 1958-10-20 1963-03-28 Minnesota Mining & Mfg Thermographisches Kopierblatt
JPS57167380A (en) * 1981-04-08 1982-10-15 Pilot Ink Co Ltd Thermochromic material
JPS62251187A (ja) * 1986-04-25 1987-10-31 Fuji Photo Film Co Ltd 感熱記録材料

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EP0614770A1 (de) 1994-09-14

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