EP0730196B1 - Matériau d'enregistrement thermosensible à propriétés stabilisatrices de l'image - Google Patents

Matériau d'enregistrement thermosensible à propriétés stabilisatrices de l'image Download PDF

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Publication number
EP0730196B1
EP0730196B1 EP19960200223 EP96200223A EP0730196B1 EP 0730196 B1 EP0730196 B1 EP 0730196B1 EP 19960200223 EP19960200223 EP 19960200223 EP 96200223 A EP96200223 A EP 96200223A EP 0730196 B1 EP0730196 B1 EP 0730196B1
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Prior art keywords
recording material
silver
reducing agent
silver salt
heat
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German (de)
English (en)
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EP0730196A2 (fr
EP0730196A3 (fr
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Luc C/O Agfa-Gevaert N.V. Leenders
Leo C/O Agfa-Gevaert N.V. Oelbrandt
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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

Definitions

  • the present invention relates to a heat-sensitive recording material being suited for use in direct thermal imaging and having image-stabilization properties.
  • 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.
  • thermosensitive imaging material A survey of "direct thermal” imaging methods is given in the book “Imaging Systems” by K.I. and R.E. Jacobson, Focal Press, London (1976), Chapter VII under the heading “7.1 Thermography”.
  • Thermography is concerned with materials which are 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.
  • thermographic system capable of providing images having an optical density more than 2.5 is based on the production of a silver metal image by means of a thermally induced oxidation-reduction reaction of a silver soap with a reducing agent.
  • US-P 3,094,417 describes a typical heat-sensitive copy-sheet product capable of undergoing permanent visible change an being momentarily heated to a conversion temperature between about 90°C and about 150°C and comprising a heat-sensitive layer containing chemically inter-reactant components in physically distinct and chemically inter-reactive relationship for inter-reaction to form a visibly distinct reaction product on heating said layer to said conversion temperature, one of said inter-reactant components being readily desensitizable against said inter-reaction by exposure, in solution in an inert solvent at a concentration just sufficient to permit distinctly visible reaction with the other of said components in said solvent, to radiation in the near-ultraviolet range of approximately 3000 to 4200 angstroms wavelength as obtained from a BH-6 high pressure mercury arc lamp at a distance of 6 inches and for a time of 45 minute, and, uniformly intermixed with said one component, a colored activatable organic photoreducible dye characterized by its ability to cause reduction of silver ion in a dilute
  • the chemically inter-reactive components to form a visibly distict reaction product on heating may be silver behenate and 4-methoxy-1-naphthol (a reducing agent) and the inter-reactant component being readily desensitizable against inter-reaction by exposure may be a mild reducing agent present in relatively high concentration.
  • Desensitization of a redox-system of light-insensitive organic silver salt and organic reducing agent, optionally in the presence of a toning agent, with "the activatable silver-reducing organic dyes" described in US-P 3,094,417 has the disadvantage of introducing background colour, dyes by definition exhibiting colour in the visible spectrum, into the image obtained by direct thermal heating and also some increase in background due to the photo-activatable silver ion reducing properties of these dyes, as described in US-P 3,094,417.
  • GB-P 1,271,177 concerns hexa-arylbiimidazole compositions and to a method for oxidizing certain oxidizable compounds and more particularly admixtures of a hexaarylbiimidazole and selected oxidizable compositions together with a method for activating, by means of heat, pressure, light or electron beam, the hexaarylbiimidazole which, in its activated free radical state, oxidizes the oxidizable composition with a formal oxidation potential of 1.35 volts or less relative to a standard calomel electrode and being selected from p-aryleneditertiaryamines, p-phenylenediamines, p-tolylenediamines, hydrazones, N-acylhydrazones, o,o'-disubstituted phenols and organic sulfhydryl compounds.
  • a heat-sensitive recording material suited for use in direct thermal imaging and having image-stabilization properties
  • material containing in a binder on a support (i) a substantially light-insensitive organic silver salt capable of thermally activated reduction to silver in thermal working relationship with (ii) at least one reducing agent capable of reducing the substantially light-insensitive organic silver salt when thermally activated
  • the recording material contains in admixture with the reducing agent(s) at least one colourless photo-oxidizing substance exclusive of tetrabromobutane capable on exposure to ultraviolet (UV) radiation, such as present in daylight or artificial lighting, of yielding free radicals capable of inactivating the reducing agent(s) by oxidation, thereby rendering the reducing agent(s) incapable of reducing the organic silver salt to silver, and not capable of reducing silver ions in a dilute solution of silver nitrate, triethanolammonium nitrate upon exposure for thirty minutes to light absorbable by the substance at about 60,000 foot-
  • UV ultraviolet
  • thermographic process comprises the steps of: (1) providing a recording material as described above; (2) bringing the recording material into contact with a heat source; (3) heating the recording material imagewise pixel by pixel; (4) separating the recording material from the heat source; and (5) uniformly exposing the imagewise heated recording material to ultraviolet radiation activating the photo-oxidizing substance to effect the oxidation of residual reducing agent.
  • thermo working relationship is meant here that the substantially light-insensitive compound, e.g. a substantially light-insensitive silver salt, and the organic reducing agent can react when the recording material is heated, i.e. at elevated temperature, to forr e.g. metallic silver.
  • the ingredients (i) and (ii) may be present in the same binder-containing layer or in different layers wherefrom by heat they can come into reactive contact with each other, e.g. by diffusion.
  • the colourless photo-oxidizing substances of the present invention that on exposure to ultraviolet (UV) radiation, such as present in daylight or artificial lighting, yield free radicals capable of inactivating the reducing agent(s) by oxidation are not capable of reducing silver ions in a dilute solution of silver nitrate, triethanolammonium nitrate upon exposure for thirty minutes to light absorbable by the substance at about 60,000 foot-candles intensity as obtained from a high intensity incandescent tungsten filament lamp.
  • UV radiation ultraviolet
  • the heat-sensitive recording material according to the present invention contains as colourless photo-oxidizing substance a bi-imidazolyl compound that on photo-exposure following thermal imaging can yield free radicals having the capability of oxidizing the reducing agent(s) that remain after thermal imaging thereby making them inactive for further reduction of the silver salt. It is surprising that such bi-imidazolyl compounds, upon photo-activation, are able to oxidize the same reducing agents which are efficient in the thermally activated reduction of substantially light-insensitive silver salts.
  • Two imidazolyl radicals that are capable of abstracting active hydrogen, so-called Zerewitinoff hydrogen, from the organic reducing agent(s) left in the non-heated areas of the present direct thermal recording material, are formed from bi-imidazolyl compounds by photo-cleavage.
  • Colourless photo-oxidizing bi-imidazolyl compounds suited for use according to the present invention correspond to following general formula : wherein : each of R 1 , R 2 and R 3 (same or different) stands for a carbocyclic or heterocyclic aromatic group, said group being free from Zerewitinoff hydrogen atoms and each dotted line circle representing 4 delocalized electrons.
  • Zerewitinoff hydrogen atoms as well known, are active hydrogen atoms that are capable of reacting with methylmagnesiumiodide.
  • the preparation of several such bi-imidazolyl compounds are described in US-P 3,734,733 and GB-P 1,271,177.
  • the bimidazolyl compounds may correspond to one of the following isomeric structures : wherein : R 1 , R 2 and R 3 have the same meaning as described above, preferably are aromatic groups, e.g. a phenyl, biphenyl, naphthyl, furyl or thienyl group, or such groups in substituted form, e.g. substituted with halogen, or R 1 , R 2 and R 3 represent a heteroaromatic saltlike system (IV) as described in published EP 0 355 335, wherein reference is made to the preparation of such type of compounds.
  • R 1 , R 2 and R 3 have the same meaning as described above, preferably are aromatic groups, e.g. a phenyl, biphenyl, naphthyl, furyl or thienyl group, or such groups in substituted form, e.g. substituted with halogen, or R 1 , R 2 and R 3 represent a heteroaromatic saltlike system (IV) as described in published
  • the biimidazolyl compound(s) are used advantageously in the heat-sensitive recording material in a molar ratio from 2:1 to 250:1 with respect to the applied reducing agent(s).
  • the biimidazolyl compounds are applied at a coverage of 0.5 to 2 g/m 2 , but the amount can be adapted according to the required stabilization that prevents the formation of background fog.
  • the bi-imidazolyl compounds are inherently sensitive to ultraviolet radiation in the wavelength range of 250 nm to 370 nm ["Imaging Systems", K.I. and R.E. Jacobson, Focal Press, London (1976), p.249].
  • the colourless photo-oxidizing substance yielding on exposure to UV-radiation oxidizing free radicals is a haloalkane exclusive of tetrabromobutane, e.g. carbon tetrabromide, iodoform or a halosulphone, e.g. tribromomethylphenylsulphone.
  • a haloalkane exclusive of tetrabromobutane e.g. carbon tetrabromide, iodoform
  • a halosulphone e.g. tribromomethylphenylsulphone.
  • haloalkanes on exposure to UV radiation bromine or iodine free radicals are formed that have oxidizing power to inactivate organic reducing agents by abstraction thereof of active hydrogen.
  • Organic reducing compounds suitable for use according to the present invention have at least one active hydrogen atom and are exemplified in the already mentioned US-P 3,734,733 and belong to one of the following classes :
  • a survey of conventional organic reducing agents containing active hydrogen attached through O, N or C is given e.g. in GB-P 1,439,478.
  • thermo-activatable reducing agents for use in combination with non-lightsensitive reducible organic silver salts are aromatic polyhydroxy spiro-bis-indane compounds, especially those disclosed in published European patent application 0 599 369, more particularly 3,3,3',3'-tetramethyl-5,6,5'6'-tetrahydroxy-1,1'-spiro-bis-indane, called furtheron "indane I”.
  • reducing agents particularly suited for use according to the present invention are organic hydroxylamine compounds corresponding to the following general formula (F) : wherein :
  • Reducing agents according to the above general formula (F) and their preparation are described in Re. 30,107 being a reissue of United States Patent No. 3,996,397.
  • Still other reducing agents particularly suited for use according to the present invention are 3,4-dihydroxybenzenes in which the benzene nucleus carries in the 1-position a substituent linked to said nucleus by means of a carbonyl group.
  • Preferred "carbonyl" substituted 3,4-dihydroxy-benzene reducing agents for use according to the present invention are less volatile than catechol and are selected from the group consisting of 3,4-dihydroxy-benzoic acid, an alkyl or aryl ester thereof, 3,4-dihydroxy-benzaldehyde, 3,4-dihydroxy-benzamide and aryl or alkyl (3,4-dihydroxyphenyl) ketones.
  • the alkyl esters of 3,4-dihydroxy-benzoic acid comprise e.g. from 1 to 18 carbon atoms, but are preferably C1-C4 alkyl esters.
  • reducing agents that itself are decomposed by ultra-violet radiation contain a group having the following structure : or contain a group having the following structure : wherein : Y represents a hydrogen atom or an acyl group.
  • Reducing agents containing that structure are described in GB-P 1,163,187 for use in a photo-thermographic recording material containing ligh-sensitive silver halide in the presence of a light-insensitive reducible organic silver salt.
  • auxiliary reducing agents are 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 bisphenols, e.g. of the type described in US-P 3,547,648.
  • the auxiliary reducing agents may be present in the imaging layer or in a polymeric binder layer adjacent thereto.
  • auxiliary reducing agents are sulfonamidophenols corresponding to the following general formula : Aryl-SO 2 -NH-Arylene-OH in which :
  • auxiliary reducing agents that may be used in conjunction with the above mentioned primary reducing agents are organic reducing metal salts, e.g. stannous stearate described in US-P 3,460,946 and 3,547,648.
  • Substantially light-insensitive organic silver salts particularly suited for use in a direct thermal recording process 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”.
  • 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 said substantially light-insensitive silver salts in combination with the above mentioned reducing agent(s) and has to be preferably such that, on heating above 100 °C, an optical density of at least 2.5 can be obtained.
  • the thickness of the imaging layer is preferably in the range of 5 to 50 ⁇ m.
  • said substantially light-insensitive organic silver salt and said organic reducing agent(s) are present in different layers.
  • the reducing agent can e.g. migrate by heat into the layer containing the organic silver salt and react therewith.
  • the reducing agent(s) is (are) applied preferably in the layer containing the photo-oxidizing agent.
  • the film-forming polymeric binder of the imaging layer of the direct thermal recording material used according to the present invention is preferably a water-insoluble thermoplastic resin or mixture of such resins, wherein the silver salt can be dispersed homogeneously.
  • a water-insoluble 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 tradename BUTVARTM B79 of Monsanto USA and provides a good adherence to paper and properly subbed polyester supports.
  • the layer containing the organic silver salt is commonly coated from an organic solvent containing the binder in dissolved form.
  • the continuous tone reproduction capability of a heat-sensitive imaging material used according to the present invention is favoured by a relatively high binder to silver salt weight ratio in the imaging layer.
  • a relatively high binder to silver salt weight ratio in the imaging layer Preferably said ratio is in the range of 1/2 to 6/1, and more preferably from 1/1 to 4/1.
  • the binder of the imaging layer may be combined with waxes or "heat solvents” also called “thermal solvents” or “thermosolvents” improving the reaction speed of the redox-reaction at elevated temperature or serving as liquid medium for the diffusion of the reducing agents in intimate contact with the organic reducible substantially light-insensitive silver salt.
  • heat solvents also called “thermal solvents” or “thermosolvents” improving the reaction speed of the redox-reaction at elevated temperature or serving as liquid medium for the diffusion of the reducing agents in intimate contact with the organic reducible substantially light-insensitive silver salt.
  • 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
  • a temperature above 60 °C 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.
  • compounds such as urea, methyl sulfonamide and ethylene carbonate being heat solvents described in US-P 3,667,959. Still other examples of heat solvents have been described in US-P 3,438,776, and 4,740,446, and in published EP-A 0 119 615 and 0 122 512 and DE-A 3 339
  • the recording layer contains in admixture with said organic silver salt and reducing agents a so-called toning agent known from thermography or photo-thermography oprating with reducible silver salts.
  • Suitable toning agents are 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 succinimides and 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 the above mentioned 3,4-dihydroxy benzene reducing agents is benzo[e][1,3]oxazine-2,4-dione described in US-P 3,951,660.
  • the imaging layer may contain other additives such as free fatty acids, antistatic agents, e.g. non-ionic antistatic agents including a fluorocarbon group as e.g. in F 3 C(CF 2 ) 6 CONH(CH 2 CH 2 O)-H, ultraviolet light absorbing compounds, white light reflecting and/or ultraviolet radiation reflecting pigments, 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 UV light absorbing compounds
  • optical brightening agents e.g., a fluorocarbon group as e.g. in F 3 C(CF 2 ) 6 CONH(CH 2 CH 2 O)-H
  • the substrate also called support for the heat-sensitive imaging layer of the thermosensitive recording material used 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 imaging layer.
  • 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 imagewise heating of the recording material according to the present invention may proceed by heat transferred imagewise from a contacting original absorbing infrared radiation in its image markings. According to more recent techniques heat is applied imagewise by one of the following embodiments.
  • the pattern-wise or imagewise heating of the recording material proceeds electrically by means of a thermal head containing an array of electrically activated micro-resistors.
  • the heating is based on the Joule effect in that selectively energized electrical resistors of a thermal head array are used in contact or close proximity with the recording layer of the thermosensitive recording material.
  • an electrically resistive ribbon consisting e.g. of a multilayered structure of a carbon-loaded polycarbonate 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 aluminium film makes direct contact with the heat-sensitive recording layer or its protective outermost layer.
  • the recording layer of said recording material is heated image-wise or pattern-wise by means of a modulated laser beam.
  • image-wise modulated laser light is used to heat the recording layer image-wise by means of substances converting absorbed laser light, e.g. infrared radiation into heat.
  • the recording layer or a layer in intimate thermo-conductive contact therewith contains light-into-heat converting substances, e.g. infrared radiation absorbing substances.
  • the imagewise 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- or pattern-wise wise heating of the recording material proceeds by means of pixelwise modulated ultra-sound, using e.g. an ultrasonic pixel printer as described e.g. in US-P 4,908,631.
  • the image signals for modulating the ultrasonic pixel printer, laser beam or electrode current 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
  • Direct thermal imaging can be used for both the production of transparencies and reflection type prints.
  • the support will be transparent or opaque, e.g. having a white light reflecting aspect.
  • a paper base is present 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 imagewise heating of the recording layer 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.
  • a protective coating is applied thereto.
  • Such coating may have the same composition as an anti-sticking coating or slipping layer which is applied in thermal dye transfer materials at the rear side of the dye donor material.
  • a slipping layer being said outermost layer may comprise a dissolved lubricating material and/or particulate material, e.g. talc particles, optionally protruding from the outermost layer.
  • suitable lubricating materials are a surface active agent, a liquid lubricant, a solid lubricant or mixtures thereof, with or without a polymeric binder.
  • 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.
  • liquid lubricants include silicone oils, synthetic oils, saturated hydrocarbons and glycols.
  • solid lubricants include various higher alcohols such as stearyl alcohol, fatty acids and fatty acid esters.
  • Suitable slipping layer compositions are described in e.g. EP 138483, EP 227090, US-P 4,567,113, US-P 4,572,860, US-P 4,717,711 and EP-A 311 841.
  • a suitable slipping layer being here an outermost layer at the recording layer side 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 (mixture) 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 EP-A 554 583.
  • 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 heat-sensitive recording layer and protective layer if applied 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.
  • thermographic recording material according to the present invention is prepared and tested as described hereinafter.
  • a subbed polyethylene terephthalate support having a thickness of 100 ⁇ m was doctor blade-coated from a solution in methyl ethyl ketone to obtain after drying the following recording layer A containing : silver behenate 7.73 g/m 2 polyvinyl butyral 3.78 g/m 2 reducing agent R as defined hereinafter 2.95 g/m 2 "indane I" as main reducing agent 0.06 g/m 2 benzo[e][1,3]oxazine-2,4-dione 0.85 g/m 2 bis(2,4,5-triphenyl-imidazole) 3.66 g/m 2 silicone oil 0.02 g/m 2
  • the non-invention recording layer B had the same composition as invention recording with the difference however that it was free from bis(2,4,5-triphenyl-imidazole).
  • Both recording materials A and B were used in a thermal printer MITSUBISHI CP100 wherein the printing proceeded while having the printing head in contact with one side of a 5 ⁇ m thick polyethylene terephthalate web (blanco web), the other side of said web being in contact with the recording layer.
  • optical densities of the thermally imaged (D max ) and non-imaged (D min ) areas were measured in transmission with densitometer Macbeth TD 904 provided with an ortho filter (maximal transmission at about 500 nm). These optical densities are given in Table 2.
  • the recording layers A and B were overall exposed with a 2000 W high-pressure mercury vapour lamp doped with FeCl 3 , and non-imaged areas were subjected to printing as described hereinbefore.
  • recording material C was the same as for recording material A with the difference however, that recording layer C had the following composition : silver behenate 7.73 g/m 2 polyvinyl butyral 3.78 g/m 2 auxiliary reducing agent R 2.95 g/m 2 main reductor M as defined hereinafter 0.19 g/m 2 benzo[e][1,3]oxazine-2,4-dione 0.85 g/m 2 bis(2,4,5-triphenyl-imidazole) 3.66 g/m 2 silicone oil 0.02 g/m 2
  • the recording material C was used likewise in a thermal printer MITSUBISHI CP100 wherein the printing proceeded while having the printing head in contact with one side of a 5 ⁇ m thick polyethylene terephthalate web (blanco web), the other side of said web being in contact with the recording layer.
  • the optical densities of the imaged (D max ) and non-imaged (D min ) areas were measured in transmission with densitometer Macbeth TD 904 provided with an ortho filter (maximal transmission at about 500 nm).
  • the recording layer C was overall exposed with a 2000 W high-pressure mercury vapour lamp doped with FeCl 3 , and non-imaged areas were subjected to printing as described hereinbefore.

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  • Materials Engineering (AREA)
  • General Physics & Mathematics (AREA)
  • Heat Sensitive Colour Forming Recording (AREA)
  • Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)

Claims (11)

  1. Matériau d'enregistrement thermosensible essentiellement non photosensible approprié pour être utilisé dans la formation d'image thermique directe et possédant des propriétés de stabilisation d'image, ledit matériau contenant dans un liant sur un support (i) un sel d'argent organique essentiellement non photosensible capable, à l'état activé par voie thermique, de subir une réduction en argent, en relation de travail thermique avec (ii) au moins un agent de réduction capable de réduire ledit sel d'argent organique essentiellement non photosensible à l'état activé par voie thermique, caractérisé en ce que ledit matériau d'enregistrement contient, en mélange avec ledit ou lesdits agents de réduction, au moins une substance photo-oxydante incolore, à l'exclusion du tétrabromobutane, capable lors d'une exposition à un rayonnement ultraviolet (UV) de générer des radicaux libres capables d'inactiver ledit ou lesdits agents de réduction par oxydation, pour ainsi rendre ledit agent ou lesdits agents de réduction incapables de réduire ledit sel d'argent organique en argent, et incapable de réduire des ions argent dans une solution diluée de nitrate d'argent et de nitrate de triéthanolammonium, lors d'une exposition pendant 30 minutes à de la lumière absorbable par la substance à une intensité d'environ 60.000 pieds-bougies telle qu'on l'obtient à partir d'une lampe à incandescence de haute intensité à filament de tungstène.
  2. Matériau d'enregistrement selon la revendication 1, dans lequel ladite substance photo-oxydante incolore est un composé de bis-imidazolyle.
  3. Matériau d'enregistrement selon la revendication 1, dans lequel ladite substance photo-oxydante incolore est un composé de bis-imidazolyle à partir duquel on obtient deux radicaux d'imidazolyle par photoclivage, qui sont capables d'extraire de l'hydrogène actif, ce que l'on appelle de l'hydrogène de Zéréwitinoff, à partir dudit ou desdits agents de réduction organiques.
  4. Matériau d'enregistrement selon la revendication 1, dans lequel ladite substance photo-oxydante incolore répond à la formule générale ci-après:
    Figure 00280001
    dans laquelle:
    chacun des radicaux R1, R2 et R3 (identiques ou- différents) représente un groupe aromatique carbocyclique ou hétérocyclique, ledit groupe étant exempt d'atomes d'hydrogène de Zéréwitinoff et chaque cercle en pointillé représentant quatre électrons délocalisés.
  5. Matériau d'enregistrement selon l'une quelconque des revendications 2 à 4, dans lequel ledit ou lesdits composés de bis-imidazolyle sont présents dans un rapport molaire de 2:1 à 250:1 par rapport à l'agent ou aux agents de réduction appliqués.
  6. Matériau d'enregistrement selon l'une quelconque des revendications précédentes, dans lequel ledit sel d'argent organique essentiellement non photosensible est un sel d'argent d'un acide carboxylique aliphatique contenant au moins 12 atomes de carbone.
  7. Matériau d'enregistrement selon la revendication 6, dans lequel ledit sel d'argent organique est le palmitate d'argent, le stéarate d'argent ou le béhénate d'argent ou encore leurs mélanges.
  8. Matériau d'enregistrement selon l'une quelconque des revendications précédentes, dans lequel ladite couche d'enregistrement contient au moins un agent influençant le ton d'image pour de l'argent métallique formé par réduction dudit sel d'argent organique.
  9. Procédé thermographique comprenant les étapes consistant à: (1) procurer un matériau d'enregistrement selon l'une quelconque des revendications 1 à 8; (2) amener ledit matériau d'enregistrement en contact avec une source de chaleur; (3) chauffer ledit matériau d'enregistrement en forme d'image pixel par pixel; (4) séparer ledit matériau d'enregistrement de ladite source de chaleur; et (5) exposer de manière uniforme ledit matériau d'enregistrement chauffé en forme d'image à un rayonnement ultraviolet activant ladite substance photo-oxydante pour mettre en oeuvre l'oxydation de l'agent de réduction résiduel.
  10. Procédé thermographique selon la revendication 9, dans lequel ledit chauffage en forme d'image a lieu par voie électrique à l'aide d'une tête thermique contenant un arrangement de microrésistances activées par voie électrique.
  11. Procédé d'enregistrement selon la revendication 9, dans lequel ledit chauffage en forme d'image a lieu à l'aide d'un faisceau laser modulé dont le rayonnement absorbé est transformé en chaleur par des substances présentes dans ledit matériau d'enregistrement.
EP19960200223 1995-03-02 1996-02-01 Matériau d'enregistrement thermosensible à propriétés stabilisatrices de l'image Expired - Lifetime EP0730196B1 (fr)

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EP95200506 1995-03-02
EP95200506 1995-03-02
EP19960200223 EP0730196B1 (fr) 1995-03-02 1996-02-01 Matériau d'enregistrement thermosensible à propriétés stabilisatrices de l'image

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EP0730196A3 EP0730196A3 (fr) 1998-01-21
EP0730196B1 true EP0730196B1 (fr) 2000-10-25

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EP0964300B1 (fr) * 1998-06-08 2003-07-09 Agfa-Gevaert Matériau d'enregistrement thermographique noir et blanc ayant un ton de l'image amélioré
US6211116B1 (en) 1998-06-08 2001-04-03 Agfa-Gevaert Substantially light-insensitive black and white thermographic recording material with improved image tone

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NL273128A (fr) * 1961-01-03
NL273129A (fr) * 1961-01-03 1900-01-01
NL300853A (fr) * 1962-11-23
US3526506A (en) * 1966-06-13 1970-09-01 Minnesota Mining & Mfg Heat reactive,light desensitizing compositions
SE354731B (fr) * 1969-03-10 1973-03-19 Nashua Corp
GB1271177A (en) * 1970-05-29 1972-04-19 Du Pont Hexaarylbiimidazole oxidation systems
BE794090A (fr) * 1972-01-17 1973-07-16 Minnesota Mining & Mfg Feuille de reproduction a sec a l'argent activee par la chaleur
JPS5941294A (ja) * 1982-09-01 1984-03-07 Fuji Photo Film Co Ltd 感熱記録方法

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EP0730196A3 (fr) 1998-01-21

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