EP1270255A1 - Produit thermographique d' enregistrement avec ton de l'image amélioré - Google Patents

Produit thermographique d' enregistrement avec ton de l'image amélioré Download PDF

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Publication number
EP1270255A1
EP1270255A1 EP02100706A EP02100706A EP1270255A1 EP 1270255 A1 EP1270255 A1 EP 1270255A1 EP 02100706 A EP02100706 A EP 02100706A EP 02100706 A EP02100706 A EP 02100706A EP 1270255 A1 EP1270255 A1 EP 1270255A1
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EP
European Patent Office
Prior art keywords
thermographic recording
recording material
molar
substituted
equivalents
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP02100706A
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German (de)
English (en)
Inventor
Philip c/o AGFA-GEVAERT Dooms
Ivan c/o AGFA-GEVAERT Hoogmartens
Geert c/o AGFA-GEVAERT Defieuw
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Agfa HealthCare NV
Original Assignee
Agfa Gevaert NV
Agfa Gevaert AG
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Filing date
Publication date
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Priority to EP02100706A priority Critical patent/EP1270255A1/fr
Publication of EP1270255A1 publication Critical patent/EP1270255A1/fr
Withdrawn legal-status Critical Current

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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
    • 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
    • G03C1/85—Photosensitive materials characterised by the base or auxiliary layers characterised by antistatic additives or coatings
    • 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
    • G03C2001/7628—Back layer

Definitions

  • the present invention relates to thermographic recording materials whose prints have improved image tone.
  • Thermal imaging or thermography is a recording process wherein images are generated by the use of thermal energy.
  • direct thermal thermography a visible image pattern is formed by image-wise heating of a recording material.
  • EP 692 733 discloses a direct thermal recording process wherein a direct thermal recording material is heated dot-wise and the direct thermal recording material comprises on a substrate an imaging layer containing uniformly distributed in a film-forming polymeric binder (i) one or more substantially light-insensitive organic silver salts being no double salts, the silver salt(s) being in thermal working relationship with (ii) an organic reducing agent therefor, characterized in that the reducing agent is a benzene compound the benzene nucleus of which is substituted by no more than two hydroxy groups which are present in 3,4-position on the nucleus and have in the 1-position of the nucleus a substituent linked to the nucleus by means of a carbonyl group.
  • the reducing agent is a benzene compound the benzene nucleus of which is substituted by no more than two hydroxy groups which are present in 3,4-position on the nucleus and have in the 1-position of the nucleus a substituent linked to the nucleus by means of
  • thermosensitive element containing a substantially light-insensitive organic silver salt, a 3,4-dihydroxybenzene compound in thermal working relationship therewith and a binder, characterized in that the 3,4-dihydroxybenzene compound is an aryloxo-3,4-dihydroxybenzene compound in which the aryl-group is substituted with at least one substituent having a ⁇ m -value greater than 0; or a heteroaryloxo-3,4-dihydroxybenzene compound in which the heteroaryl group has a unified aromaticity index I A greater than 53 and is optionally substituted with at least one group selected from the group consisting of aryl, hydroxy, carboxy, sulfo, sulfoalkyl, sulfoaryl, sulfonylalkyl, sulfonylaryl,
  • thermosensitive element containing a substantially light-insensitive organic silver salt, a 1,2-dihydroxybenzene-compound in thermal working relationship therewith and a binder, characterized in that the 1,2-dihydroxybenzene-compound is represented by formula (I): R 1 SO 2 R 2 , wherein R 1 is an optionally substituted aryl group and R 2 is selected from the group consisting of a 3,4,5-trihydroxyphenyl group, a 3-alkoxy-4,5-dihydroxyphenyl group and a 3-aryloxy-4,5-dihydroxyphenyl group; or the 1,2-dihydroxybenzene-compound is represented by formula (II): R 3 COOR 4 , wherein R 3 is a 3-alkoxy-4,5-dihydroxyphenyl group or a 3-aryloxy-4,5-dihydroxyphenyl group;
  • US 3,028,254 discloses heat-sensitive copy-sheets comprising a substantially light-insensitive organic silver salt, a reducing agent therefor and a binder. Specifically in Example 1 molar ratio of molar hydroxy-equivalents of reducing agents to molar silver-equivalents of the substantially light-insensitive organic silver salts of 1.78 and 1.33 are disclosed with respect to 3,3,3',3'-tetramethyl-1,1'-spiro-bis-indane 5,5',6,6'-tetrol and behenyl pyrogallol and silver behenate; and 3,3,3',3'-tetramethyl-1,1'-spiro-bis-indane 5,5',6,6'-tetrol and silver behenate respectively.
  • US 3,031,329 discloses heat-sensitive copy-sheets comprising a substantially light-insensitive organic silver salt, a reducing agent therefor and a binder. Specifically in Examples 1 and 2 molar ratios of molar hydroxy-equivalents of reducing agents to molar silver-equivalents of the substantially light-insensitive organic silver salts of 7.29 and 4.13 are disclosed respectively with respect to 3,3,3',3'-tetramethyl-1,1'-spiro-bis-indane 5,5',6,6'-tetrol, 3,4-dihydroxybenzoic acid and silver behenate; and methyl gallate and silver behenate respectively.
  • US 3,074,809 discloses heat-sensitive copy-sheets comprising a substantially light-insensitive organic silver salt, a reducing agent therefor and a binder. Specifically in Examples 1, 2 and 3 molar ratios of molar hydroxy-equivalents of reducing agents to molar silver-equivalents of the substantially light-insensitive organic silver salts of 5.725, 5.725 and 2.310 are disclosed respectively with respect to hydroquinone and silver behenate; hydroquinone and silver behenate; and methyl gallate, 2,3-dihydroxybenzoic acid and silver behenate respectively.
  • US 3,103,881 discloses heat-sensitive copy-sheets comprising a substantially light-insensitive organic silver salt, a reducing agent therefor and a binder. Specifically in Example 3 a molar ratio of molar hydroxy-equivalents of reducing agents to molar silver-equivalents of the substantially light-insensitive organic silver salts of 2.95 is disclosed with respect to 3,4-dihydroxybenzoic acid and silver behenate.
  • US 3,107,174 discloses heat-sensitive copy-sheets comprising a substantially light-insensitive organic silver salt, a reducing agent therefor and a binder. Specifically in Example 1 a molar ratio of molar hydroxy-equivalents of reducing agents to molar silver-equivalents of the substantially light-insensitive organic silver salts of 3.29 is disclosed with respect to methyl gallate and silver behenate.
  • thermographic recording materials it is therefore an aspect of the present invention to provide concepts to enable substantially light-insensitive thermographic recording materials to be developed whose prints exhibit both satisfactory archivability and image tone.
  • thermographic recording materials It is a further aspect of the present invention to provide concepts to enable substantially light-insensitive thermographic recording materials to be developed which upon printing with a thermal head printer with a heating time ⁇ 15 ms produce prints exhibiting both satisfactory archivability and image tone.
  • thermographic recording process for a monosheet black and white substantially light-insensitive thermographic recording material according to any of the preceding claims comprising the steps of: (i) providing the thermographic recording material; (ii) bringing the thermographic recording material into the proximity of a heat source; (iii) applying heat imagewise from the heat source to the thermographic recording material; and (iv) removing the thermographic recording material from the proximity of the heat source.
  • the heat source is a thermal head.
  • the heat source is a thin film thermal head.
  • the heat source is a thin film thermal head operating with heating time of ⁇ 25 ms.
  • the heat source is a thin film thermal head operating with heating time of ⁇ 15 ms.
  • alkyl means all variants possible for each number of carbon atoms in the alkyl group i.e. for three carbon atoms: n-propyl and isopropyl; for four carbon atoms: n-butyl, isobutyl and tertiary-butyl; for five carbon atoms: n-pentyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl and 2-methyl-butyl etc.
  • Annelated means having a carbon-carbon bond in common with e.g. annelation of a benzene ring with a naphthalene ring results in anthracene or phenanthrene depending on which carbon-carbon bond in the naphthalene ring is common to both the naphthalene ring and the benzene ring.
  • substantially light-insensitive is meant not intentionally light sensitive.
  • the unified aromaticity index I A is described by C.W. Bird in Tetrahedron, 48(32), 335-340 (1992), which also discloses aromaticity index values for a large range of aromatic groups.
  • the molar hydroxy-equivalents of a 1,2-dihydroxybenzene compound is obtained by multiplying the molar concentration of the 1,2-dihydroxybenzene compound by the number of hydroxy-groups substituents on benzene rings in formula (I) and then adding these values together.
  • ethyl 3,4-dihydroxybenzoate has two molar hydroxy-equivalents per mole
  • n-propyl gallate with the benzene ring substituted with three hydroxy-groups has three molar hydroxy-equivalents per mole
  • 3,3,3',3'-tetramethyl-1,1'-spiro-bis-indane 5,5',6,6'-tetrol with two benzene rings each substituted with two hydroxy-groups has four molar hydroxy-equivalents per mole.
  • the molar silver-equivalent of a substantially light-insensitive organic silver salt is obtained by multiplying the molar concentration of the substantially light-insensitive organic silver salt by the number of silver-atoms in the particular substantially light-insensitive organic silver salt e.g. silver behenate has one molar silver-equivalent per mole and silver adipate, being a silver salt of a dicarboxylic acid, has two molar silver-equivalents per mole.
  • the molar ratio of the molar hydroxy-equivalent of the 1,2-dihydroxybenzene compound to the molar silver-equivalent of the substantially light-insensitive organic silver salt is obtained by dividing the molar hydroxy-equivalent of the 1,2-dihydroxybenzene compound, obtained as described above, by the molar silver-equivalents of the substantially light-insensitive organic silver salt, obtained as described above.
  • the molar ratio of molar hydroxy-equivalents of the 1,2-dihydroxybenzene compounds to molar silver-equivalents of the substantially light-insensitive organic silver salts is determined by dividing the sum of the hydroxy-equivalents of the 1,2-dihydroxybenzene compounds present by the sum of the silver-equivalents of the substantially light-insensitive organic silver salts present.
  • the total line time of a thermal head is the time between the beginning of the printing of one line of pixels and the beginning of the printing of the next line of pixels in the printer transport direction.
  • the total line time is equal to the active line time if no cooling time is included in the total line time. Should a cooling time be included in total line time, this cooling time should be subtracted from the total line time to obtain the active line time.
  • This heating time corresponds to the time during which the film element experiences heat.
  • substantially water-free condition means heating at a temperature of 80 to 250°C.
  • substantially water-free condition means that the reaction system is approximately in equilibrium with water in the air, and water for inducing or promoting the reaction is not particularly or positively supplied from the exterior to the element. Such a condition is described in T.H. James, "The Theory of the Photographic Process", Fourth Edition, Macmillan 1977, page 374.
  • the molar ratio of molar hydroxy-equivalents of the 1,2-dihydroxybenzene compounds to molar silver-equivalents of the substantially light-insensitive organic silver salts is 1.3 to 5.0.
  • the molar ratio of molar hydroxy-equivalents of the 1,2-dihydroxybenzene compounds to molar silver-equivalents of the substantially light-insensitive organic silver salts is 1.3 to 4.0.
  • the molar ratio of molar hydroxy-equivalents of the 1,2-dihydroxybenzene compounds to molar silver-equivalents of the substantially light-insensitive organic silver salts is 1.5 to 3.5.
  • the molar ratio of molar hydroxy-equivalents of the 1,2-dihydroxybenzene compounds to molar silver-equivalents of the substantially light-insensitive organic silver salts is 1.5 to 3.0.
  • the molar ratio of molar hydroxy-equivalents of the 1,2-dihydroxybenzene compounds to molar silver-equivalents of the substantially light-insensitive organic silver salts is 1.5 to 2.5.
  • the molar ratio of molar hydroxy-equivalents of the 1,2-dihydroxybenzene compounds to molar silver-equivalents of the substantially light-insensitive organic silver salts is 1.3 to 2.0.
  • R 1 and R 2 are independently an alkyl, a substituted alkyl, an aryl, a substituted aryl group, an alkoxy, a substituted alkoxy, an aryloxy, a substituted aryloxy, a hydroxy group, an amino group or a substituted amino group;
  • R 3 is an alkyl, a substituted alkyl, an aryl, a substituted aryl, an amino or a substituted amino group;
  • R 4 is an alkyl, a substituted alkyl, an aryl or a substituted aryl group or hydrogen;
  • R 5 is an alkyl, a substituted alkyl, an aryl or a substituted aryl group or hydrogen
  • the 1,2-dihydroxybenzene-compounds are selected from the group consisting of 3,4-dihydroxybenzoate alkyl and aryl esters, 3,4-dihydroxybenzophenone, 3,4-dihydroxybenzophenone compounds in which the benzene ring without hydroxy-group substituents is substituted with at least one substituent having a Hammett ⁇ m -constant > 0 and ⁇ 0.85, 3,4-dihydroxy-acetophenone and 3,4-dihydroxybenzonitrile.
  • the 1,2-dihydroxybenzene compounds according to formula (I) are selected from the reducing agents disclosed in EP-B 692 733, EP-A 903 625 and unpublished European Patent Application Nr. EP01000096.6.
  • thermosensitive element contains more than one of the 1,2-dihydroxybenzene compounds according to formula (I) and one of the 1,2-dihydroxybenzene compounds according to formula (I) is 1,2-dihydroxybenzonitrile.
  • the 1,2-dihydroxybenzene compounds according to formula (I) are 3,4-dihydroxybenzonitrile and 3,4-dihydroxybenzophenone.
  • the 1,2-dihydroxybenzene compounds according to formula (I) is an alkyl 3,4-dihydroxybenzoate such as ethyl 3,4-dihydroxybenzoate and n-butyl 3,4-dihydroxybenzoate.
  • Suitable 1,2-dihydroxybenzene compounds according to the present invention are:
  • thermosensitive element as used herein is that element which contains all the ingredients which contribute to image formation.
  • the thermosensitive element contains one or more substantially light-insensitive organic silver salts, one or more 1,2-dihydroxybenzene-compounds as reducing agents therefor in thermal working relationship therewith and a binder.
  • the element may comprise a layer system in which the above-mentioned ingredients may be dispersed in different layers, with the proviso that the substantially light-insensitive organic silver salts are in reactive association with the reducing agents i.e. during the thermal development process the reducing agent must be present in such a way that it is able to diffuse to the particles of substantially light-insensitive organic silver salt so that reduction to silver can occur.
  • the organic silver salts are not double organic salts containing a silver cation associated with a second cation e.g. magnesium or iron ions.
  • At least one of the organic silver salts is a substantially light-insensitive silver salt of an organic carboxylic acid.
  • At least one of the organic silver salts is a substantially light-insensitive silver salt of an aliphatic carboxylic acids known as a fatty acid, 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".
  • Other silver salts of an organic carboxylic acid as described in GB-P 1,439,478, e.g. silver benzoate may likewise be used to produce a thermally developable silver image.
  • Combinations of different silver salt of an organic carboxylic acids may also be used in the present invention, as disclosed in EP-A 964 300.
  • Organic silver salts may be dispersed by standard dispersion techniques. Ball mills, bead mills, microfluidizers, ultrasonic apparatuses, rotor stator mixers etc. have been found to be useful in this regard. Mixtures of organic silver salt dispersions produced by different techniques may also be used to obtain the desired thermographic properties e.g. of coarser and more finely ground dispersions of organic silver salts.
  • thermosensitive element contains a reducing agent in addition to 1,2-dihydroxybenzene compounds according to formula (I).
  • thermosensitive element further contains at least one reducing agent disclosed in unpublished European Patent Application Nr. EP01000095.8, such as: 4-methyl-3',4',5'-trihydroxy-diphenylsulphone.
  • thermosensitive element Binder of the thermosensitive element
  • the film-forming binder of the thermosensitive element may be all kinds of natural, modified natural or synthetic resins or mixtures of such resins, in which the substantially light-insensitive organic silver salt can be dispersed homogeneously either in aqueous or solvent media: e.g. cellulose derivatives such as ethylcellulose, cellulose esters, e.g.
  • cellulose nitrate carboxymethylcellulose, starch ethers, galactomannan
  • 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 alcohol, 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, polystyrene and polyethylene or mixtures thereof.
  • the thermosensitive element contains a binder which does not contain additives or impurities which adversely affect the thermographic properties of the thermographic recording materials in which they are used.
  • thermosensitive element further contains a so-called toning agent organic silver salt in order to obtain a neutral black image tone in the higher densities and neutral grey in the lower densities.
  • Suitable toning agents are described in US 3,074,809, US 3,446,648 and US 3,844,797 and US 4,082,901.
  • Other particularly useful toning agents are the heterocyclic toning compounds of the benzoxazine dione or naphthoxazine dione type as disclosed in GB 1,439,478, US 3,951,660 and US 5,599,647.
  • the thermosensitive element further contains one or more toning agents selected from the group consisting of phthalazinone, benzo[e][1,3]oxazine-2,4-dione, 7-methyl-benzo[e][1,3]oxazine-2,4-dione, 7-methoxy-benzo[e][1,3]oxazine-2,4-dione and 7-(ethylcarbonato)-benzo[e][1,3]oxazine-2,4-dione.
  • phthalazinone benzo[e][1,3]oxazine-2,4-dione
  • 7-methyl-benzo[e][1,3]oxazine-2,4-dione 7-methoxy-benzo[e][1,3]oxazine-2,4-dione
  • 7-(ethylcarbonato)-benzo[e][1,3]oxazine-2,4-dione
  • Stabilizers may be incorporated into the substantially light-insensitive thermographic recording materials of the present invention in order to obtain improved shelf-life and reduced fogging.
  • the thermosensitive element further contains at least one stabilizer selected from the group consisting of benzotriazole; substituted benzotriazoles; tetrazoles; mercaptotetrazoles, such as 1-phenyl-5-mercapto-tetrazole; and aromatic polycarboxylic acids, such as ortho-phthalic acid, 3-nitro-phthalic acid, tetrachlorophthalic acid, mellitic acid, pyromellitic acid and trimellitic acid, and anhydrides thereof.
  • stabilizer selected from the group consisting of benzotriazole; substituted benzotriazoles; tetrazoles; mercaptotetrazoles, such as 1-phenyl-5-mercapto-tetrazole; and aromatic polycarboxylic acids, such as ortho-phthalic acid, 3-nitro-phthalic acid, tetrachlorophthalic acid, mellitic acid, pyromellitic acid and trimellitic acid, and anhydrides thereof.
  • the thermosensitive element further comprises at least one optionally substituted aliphatic (saturated as well as unsaturated aliphatic and also cycloaliphatic) polycarboxylic acid and/or anhydride thereof in a molar percentage of at least 15 with respect to all the organic silver salt(s) present and in thermal working relationship therewith.
  • the polycarboxylic acid may be used in anhydride form or partially esterified form on the condition that at least two free carboxylic acids remain or are available in the heat recording step.
  • the thermosensitive element further contains glutaric acid.
  • thermographic recording materials of the present invention may contain one or more surfactants, which may be anionic, non-ionic or cationic surfactants and/or one or more dispersants.
  • the recording material may contain in addition to the ingredients mentioned above other additives such as levelling agents e.g. BAYSILONTM MA (from BAYER AG, GERMANY).
  • levelling agents e.g. BAYSILONTM MA (from BAYER AG, GERMANY).
  • the support for the thermosensitive element according to the present invention may be transparent, translucent or opaque and is a thin flexible carrier made of transparent resin film, e.g. made of a cellulose ester, cellulose triacetate, polypropylene, polycarbonate or polyester, e.g. polyethylene terephthalate.
  • transparent resin film e.g. made of a cellulose ester, 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 thermosensitive element. It may be pigmented with a blue pigment as so-called blue-base.
  • One or more backing layers may be provided to control physical properties such as curl and static.
  • thermosensitive element is provided with a protective layer to avoid local deformation of the thermosensitive element and to improve resistance against abrasion.
  • thermosensitive element is provided with a protective layer comprising a binder, which may be solvent-soluble, solvent-dispersible, water-soluble or water- dispersible.
  • a binder which may be solvent-soluble, solvent-dispersible, water-soluble or water- dispersible.
  • thermosensitive element is provided with a protective layer comprising solvent-soluble polycarbonates as binders, as described in EP-A 614 769.
  • the thermosensitive element is provided with a protective layer comprising a water-soluble or water-dispersible binder, as coating can be performed from an aqueous composition and mixing of the protective layer with the immediate underlayer can be avoided by using a solvent-soluble or solvent-dispersible binder in the immediate underlayer.
  • the protective layer according to the present invention may be crosslinked. Crosslinking can be achieved by using crosslinking agents such as described in WO 95/12495. Solid or liquid lubricants or combinations thereof are suitable for improving the slip characteristics of the thermographic recording materials according to the present invention.
  • the thermosensitive element is provided with a protective layer comprising a solid thermomeltable lubricant such as those described in WO 94/11199.
  • the protective layer of the thermographic recording material according to the present invention may comprise a matting agent.
  • the thermosensitive element is provided with a protective layer comprising a matting agent such as described in WO 94/11198, e.g. talc particles, and optionally protrude from the protective layer.
  • the support on the opposite side of the support to the thermosensitive element, is provided with an adhesion layer containing an intrinsically conducting polymer.
  • the adhesion layer contains a binder e.g. a latex binder and a colloidal pigment e.g. colloidal silica.
  • the support on the opposite side of the support to the thermosensitive element, is provided with an adhesion layer containing an intrinsically conducting polymer and the adhesion layer is provided with a backing layer optionally containing a second intrinsically conducting polymer.
  • the backing layer contains a binder e.g. poly(vinyl alcohol), poly(methyl methacrylate) and gelatine, a pigment e.g. colloidal silica, and a matting agent e.g. silica particles or polymer particles e.g. poly(methyl methacrylate) particles.
  • the support on the opposite side of the support to the thermosensitive element, is provided with an adhesion layer containing an intrinsically conducting polymer and the adhesion layer is provided with a backing layer optionally containing a second intrinsically conducting polymer and the intrinsically conducting polymer and/or the second intrinsically conducting polymer is a polythiophene.
  • the support on the opposite side of the support to the thermosensitive element, is provided with an adhesion layer containing an intrinsically conducting polymer and the adhesion layer is provided with a backing layer optionally containing a second intrinsically conducting polymer and the intrinsically conducting polymer and/or the second intrinsically conducting polymer is a polythiophene, which is a polymer or copolymer of a 3,4-dialkoxythiophene in which said two alkoxy groups may be the same or different or together represent an optionally substituted oxy-alkylene-oxy bridge e.g. poly(3,4-ethylenedioxythiophene).
  • the pH of the dispersion for coating the outermost layer of the same side of the support as the thermosensitive element be less than 5 and substantially identical to that of the dispersion for coating the outermost layer of the side of the support opposite to that of the thermosensitive element. This results in a similar surface pH from the outermost layers on both sides of the support.
  • any layer of the recording material of the present invention may proceed by any coating technique e.g. such as described in Modern Coating and Drying Technology, edited by Edward D. Cohen and Edgar B. Gutoff, (1992) VCH Publishers Inc. 220 East 23rd Street, Suite 909 New York, NY 10010, U.S.A.
  • Thermographic imaging is carried out by the image-wise application of heat either in analogue fashion by direct exposure through an image or by reflection from an image, or in digital fashion pixel by pixel either by using an infra-red heat source, for example with a Nd-YAG laser or other infra-red laser, with a substantially light-insensitive thermographic material preferably containing an infra-red absorbing compound, or by direct thermal imaging with a thermal head.
  • thermal printing image signals are converted into electric pulses and then through a driver circuit selectively transferred to a thermal printhead.
  • the thermal printhead consists of microscopic heat resistor elements, which convert the electrical energy into heat via Joule effect.
  • the operating temperature of common thermal printheads is in the range of 300 to 400°C and the heating time per picture element (pixel) may be less than 1.0ms, the pressure contact of the thermal printhead with the recording material being e.g. 200-500g/cm 2 to ensure a good transfer of heat.
  • the image-wise heating of the recording material with the thermal printing heads may proceed through a contacting but removable resin sheet or web wherefrom during the heating no transfer of recording material can take place.
  • Activation of the heating elements can be power-modulated or pulse-length modulated at constant power.
  • EP-A 654 355 discloses a method for making an image by image-wise heating by means of a thermal head having energizable heating elements, wherein the activation of the heating elements is executed duty cycled pulsewise.
  • EP-A 622 217 discloses a method for making an image using a direct thermal imaging element producing improvements in continuous tone reproduction.
  • Image-wise heating of the recording material can also be carried out using an electrically resistive ribbon incorporated into the material.
  • Image- or pattern-wise heating of the recording material may also proceed by means of pixel-wise modulated ultrasound.
  • Thermographic imaging can be used for the production of reflection type prints and transparencies, in particular for use in the medical diagnostic field in which black-imaged transparencies are widely used in inspection techniques operating with a light box.
  • thermosensitive element Preparation of the thermosensitive element
  • thermosensitive elements of the substantially light-insensitive thermographic recording materials of COMPARATIVE EXAMPLES 1 to 12 and INVENTION EXAMPLES 1 to 11 were produced by coating a dispersion with the following ingredients in 2-butanone onto a subbed 168 ⁇ m thick blue-pigmented polyethylene terephthalate support with CIELAB a*- and b*- values of -7.9 and -16.6 respectively; and drying at 50°C for 1h in a drying cupboard to produce layers with the compositions given in Table 1. Comparative example nr.
  • thermosensitive elements of the thermographic recording materials of COMPARATIVE EXAMPLES 1 to 12 and INVENTION EXAMPLES 1 to 11 were then coated with an aqueous composition with the following ingredients to produce a layer with the following ingredient coverages as solids after drying:
  • the pH of the coating composition was adjusted to a pH of 3.8 by adding IN nitric acid. Those lubricants which were insoluble in water, were dispersed in a ball mill with, if necessary, the aid of a dispersion agent.
  • the composition was coated to a wet layer thickness of 85mm and then dried at 40°C for 15 minutes and hardened for 7 days at 45°C and a relative humidity of 70% thereby producing the thermographic recording materials of COMPARATIVE EXAMPLES 1 to 12 and INVENTION EXAMPLES 1 to 11.
  • the thermal head resistors were power-modulated to produce different image densities.
  • the image tone of fresh prints made with the substantially light-insensitive thermographic recording materials of COMPARATIVE EXAMPLES 1 to 12 and INVENTION EXAMPLES 1 to 11 using printer modes 1, 2 and 3 was assessed on the basis of the L*, a* and b* CIELAB-values.
  • the L*, a* and b* CIELAB-values were determined by spectrophotometric measurements according to ASTM Norm E179-90 in a R(45/0) geometry with evaluation according to ASTM Norm E308-90.
  • the b* CIELAB-values changed little between the printer modes and as a function of the ratio of molar hydroxy-equivalents to molar silver equivalents.
  • a negative CIELAB a*-value indicates a greenish image-tone becoming greener as a* becomes more negative, a positive a*-value indicating a reddish image-tone becoming redder as a* becomes more positive.
  • a negative CIELAB b*-value indicates a bluish tone which becomes increasingly bluer as b* becomes more negative and a positive b*-value indicates a yellowish image-tone becoming more yellow as b* becomes more positive.
  • the image tone of elements of the image with a density of 1.0 have a stronger effect than the image tone of elements with lower or higher optical density.
  • thermographic recording materials with all the reducing agents investigated surprisingly exhibited CIELAB a*-values which very strongly decreased with increasing ratio of molar hydroxy-equivalents to molar silver-equivalents in the range 1.0 to about 3.0. Above a ratio of 3.0 the change in CIELAB a*-value was much lower.
  • Table 4 shows that substantially light-insensitive thermographic recording materials of INVENTION EXAMPLES 1 to 11 and COMPARATIVE EXAMPLES 9 and 11 with reducing agents I-6, I-13 and I-14, exhibit neutral to bluish image tones. However, this is clearly not the case for the substantially light-insensitive thermographic recording materials of COMPARATIVE EXAMPLES 1 to 6 with reducing agents CR01 and CR02, which exhibited strongly reddish image tones.
  • the present invention is demarcated with respect to the prior art by the surprising decrease in a* CIELAB-values with increasing ratio of molar hydroxy-equivalents to molar silver-equivalents together with the deterioration in archivability for a ratio of molar hydroxy-equivalents to molar silver-equivalents of 7.0, see the ⁇ b* CIELAB-values for COMPARATIVE EXAMPLE 9 and COMPARATIVE EXAMPLE 11 compared with those for INVENTION EXAMPLES 7 and 9 respectively for printer modes 1, 2 and 3.
  • thermosensitive element Preparation of the thermosensitive element
  • thermosensitive elements of the substantially light-insensitive thermographic recording materials of COMPARATIVE EXAMPLE 13 and INVENTION EXAMPLES 12 and 13 were produced by coating a dispersion with the following ingredients in 2-butanone onto a subbed 168 ⁇ m thick blue-pigmented polyethylene terephthalate support with CIELAB a*- and b*- values of -7.9 and -16.6 respectively; and drying at 75°C (temperature of the dry air) for 7 minutes to produce layers with the compositions given in Table 6.
  • thermosensitive elements of the thermographic recording materials of COMPARATIVE EXAMPLE 13 and INVENTION EXAMPLES 12 and 13 were coated with a protective layer as described for the thermographic recording materials of COMPARATIVE EXAMPLES 1 to 12 and INVENTION EXAMPLES 1 to 11 and the resulting thermographic recording materials hardened for 7 days at 45°C thereby producing the thermographic recording materials of COMPARATIVE EXAMPLE 13 and INVENTION EXAMPLES 12 and 13.
  • thermographic recording materials of COMPARATIVE EXAMPLE 13 and INVENTION EXAMPLES 12 and 13 were printed with DRYSTARTM 4500 printer mode 3 and evaluated as described for the thermographic recording materials of COMPARATIVE EXAMPLES 1 to 12 and INVENTION EXAMPLES 1 to 11. The results are summarized in Table 7.
  • thermosensitive element Preparation of the thermosensitive element
  • thermosensitive elements of the substantially light-insensitive thermographic recording materials of COMPARATIVE EXAMPLES 14 and 15 and INVENTION EXAMPLES 14 and 15 were produced by coating a dispersion with the following ingredients in 2-butanone onto a subbed 168 ⁇ m non-pigmented polyethylene terephthalate support; and drying at 50°C for 1 hour to produce layers with the compositions given in Table 9. Comparative example nr.
  • thermographic recording materials containing reducing agent I-6 upon printing with the DRYSTARTM 2000 printer mode 1 for a ratio of molar hydroxy-equivalents to molar silver equivalents of 1.5, despite the thermographic materials having been coated on a non-pigmented support, whereas thermographic recording materials containing reducing agents I-6 upon printing with the DRYSTARTM 2000 printer mode 2 for a ratio of molar hydroxy-equivalents to molar silver equivalents of 1.0 exhibited prohibitively reddish images as can be seen from the pronouncedly positive CIELAB a*-values.
  • the subbed support was prepared by coating a 175 ⁇ m thick blue-pigmented polyethylene terephthalate support with L*, a* and b* CIELAB-values of 86.7, -8.2 and -18.2 respectively and a density through a visible filter determined with a MacBethTM 924 of 0.19 on both sides with a layer with an aqueous ethanol dispersion containing the following ingredients to produce the following ingredient coverages as solids after drying: Coverage [mg/m 2 ] LATEX01: 162.2 Kieselsol 100F: 40.0 MersolatTM H 0.85 UVONAC 4.0
  • a backing layer was then applied to one side of the subbed support with an aqueous ammoniacal N-methyl-pyrrolidinone dispersion containing the following ingredients to produce the following ingredient coverages as solids after drying: Coverage [mg/m 2 ] KelzanTM S 10 PEDOT/PSS-1 15 UVONAC 21 Kieselsol 100F 20 PerapretTM 10 LATEX02 200 MAT02 30
  • thermosensitive elements of the substantially light-insensitive thermographic recording materials of COMPARATIVE EXAMPLE 16 was produced by coating a dispersion with the following ingredients in 2-butanone to a wet thickness of 95 ⁇ m onto the side of the subbed support opposite to that to which the backing layer had been applied, and drying at 85°C for 5 minutes to produce a layer with the following composition: Coverage [g/m 2 ] mol% vs AgB AgB 3.809 100 BL5HP 15.202 - I-6 0.768 49.50 T01 0.209 15.06 T02 0.107 5.02 S01 0.271 24.08 S02 0.120 4.94 S03 0.100 9.85 Oil 0.025 -
  • thermosensitive elements of the thermographic recording material of COMPARATIVE EXAMPLE 16 was produced by coating an aqueous dispersion with the following ingredients onto the thermosensitive element to give a layer with the following ingredient coverages as solids after drying:
  • the pH of the coating composition was adjusted to a pH of 3.8 by adding IN nitric acid.
  • thermographic recording material COMPARATIVE EXAMPLE 16.
  • thermographic recording materials of COMPARATIVE EXAMPLE 16 was printed with DRYSTARTM 4500 printer modes 1, 2 and 3 and evaluated as described for the thermographic recording materials of COMPARATIVE EXAMPLES 1 to 12 and INVENTION EXAMPLES 1 to 11. The results are summarized in Table 14.
  • the subbed support was prepared by coating a 168 ⁇ m thick blue-pigmented polyethylene terephthalate support with L*, a* and b* CIELAB-values of 86.7, -8.2 and -18.2 respectively and a density through a visible filter determined with a MacBethTM 924 of 0.19 on one side with a non-antistatic layer with an aqueous dispersion containing the following ingredients to produce the following ingredient coverages as solids after drying: Coverage [mg/m 2 ] LATEX03: 151 Kieselsol 100F: 35 MersolatTM H 0.75 and on the other side with an antistatic layer with an aqueous dispersion containing the following ingredients to produce the following ingredient coverages as solids after drying: Coverage [mg/m 2 ] PEDOT/PSS-2: 2.58 LATEX03: 147.3 Sorbitol(evaporated during drying): 24.7 Kieselsol 100F: 16.4 MersolatTM H 0.74
  • thermographic recording materials of INVENTION EXAMPLES 16 to 18 were prepared by producing a 13.2% by weight aqueous solution of POVALTM 103 by adding 264 g to 1736 g of cold deionized water, heating to 95°C and maintaining this temperature for 30 minutes before cooling to room temperature. This solution was then mixed with 1067.6 g of deionized water followed by 130.7 mL of a 5% solution of OP80 with mixing, then 1978.5 g of SnowtexTM O with mixing and finally 45.85 g of MAT01 with mixing.
  • the pH of the resulting dispersion was 4.8 and was adjusted to a pH of 3.5 with IN nitric acid before coating to a wet thickness of 40 ⁇ m on the antistatic subbing layer of the support.
  • thermosensitive element of the substantially light-insensitive thermographic recording materials of INVENTION EXAMPLES 16 to 18 was produced by coating a dispersion to a wet thickness of 95 ⁇ m with the following ingredients in 2-butanone onto the opposite side of the support to which the backing layer had been applied, and drying at 85°C for 5 minutes to produce a layer with the following composition: Coverage [g/m 2 ] mol% vs AgB AgB 4.149 100 BL5HP 16.596 - I-1 0.438 35.00 I-13 0.894 45.00 T03 0.246 15.06 S01 0.294 24.00 S02 0.130 4.91 S03 0.109 9.84 VL 0.185 - Oil 0.037 -
  • thermosensitive elements of the thermographic recording materials of INVENTION EXAMPLES 16 to 18 were then coated with an aqueous dispersion with the following ingredients onto the thermosensitive element with the protective layers with the ingredient coverages as solids after drying given for the thermographic recording materials for INVENTION EXAMPLES 16 to 18 in Table 18.
  • the pH of the coating composition was adjusted to a pH of 3.8 by adding IN nitric acid. Those lubricants which were insoluble in water, were dispersed in a ball mill with, if necessary, the aid of a dispersion agent.
  • the composition was coated to a wet layer thickness of 85 ⁇ m and then dried at 40°C for 15 minutes and hardened for 7 days at 50°C thereby producing the thermographic recording materials of INVENTION EXAMPLES 16 to 18.
  • thermographic recording materials of COMPARATIVE EXAMPLE 16 was printed with DRYSTARTM 4500 printer modes 1, 2 and 3 and evaluated as described for the thermographic recording materials of COMPARATIVE EXAMPLES 1 to 12 and INVENTION EXAMPLES 1 to 11. The results are summarized in Table 19.
  • the changes in b* CIELAB-values were acceptable even in the case of prints produced with DRYSTARTM 4500 Printer mode 3 with the lowest line and heating times.
  • thermographic recording materials of INVENTION EXAMPLE 19 was printed with DRYSTARTM 4500 printer modes 1, 2 and 3 and evaluated as described for the thermographic recording materials of COMPARATIVE EXAMPLES 1 to 12 and INVENTION EXAMPLES 1 to 11. The results are summarized in Table 23.
  • the changes in b* CIELAB-values were acceptable even in the case of prints produced with DRYSTARTM 4500 Printer mode 3 with the lowest line and heating times.
  • the subbed support was prepared by coating a 175 ⁇ m thick blue-pigmented polyethylene terephthalate support with L*, a* and b* CIELAB-values of 86.7, -8.2 and -18.2 respectively and a density through a visible filter determined with a MacBethTM 924 of 0.19 with the non-antistatic and antistatic subbing layers described for the support of INVENTION EXAMPLES 16 to 18.
  • a backing layer was applied to the antistatic layer of the support with an aqueous dispersion containing the following ingredients to produce the following ingredient coverages as solids after drying: Coverage [mg/m 2 ] KELZANTM S 10 PEDT/PSS-2 12 ZonylTM FSO 100 21 Kieselsol 100F 20 PoligenTM WE7 10 LATEX04 1000 MAT01 30
  • thermosensitive element Preparation of the thermosensitive element
  • thermosensitive elements of the substantially light-insensitive thermographic recording materials of INVENTION EXAMPLE 20 was produced by coating a dispersion with the following ingredients in 2-butanone onto the opposite site of the support to the backing layer, and drying at 85°C for 5 minutes to produce layers with the following composition: Coverage [g/m 2 ] mol% vs AgB AgB 4.10 100 BL5HP 16.40 - I-1 0.37 29.67 I-6 0.81 48.34 T02 0.12 5.00 T03 0.26 15.00 S01 0.29 23.98 S02 0.13 4.94 S03 0.11 9.85 Oil 0.036 - The thermosensitive element was coated with the same protective layer as described for COMPARATIVE EXAMPLE 16.
  • thermographic recording materials of INVENTION EXAMPLE 20 was printed with DRYSTARTM 4500 printer modes 1, 2 and 3 and evaluated as described for the thermographic recording materials of COMPARATIVE EXAMPLES 1 to 12 and INVENTION EXAMPLES 1 to 11. The results are summarized in Table 27.
  • the change in b* CIELAB-value for prints produced using DRYSTARTM 4500 Printer modes 1, 2 or 3 during the archivability tests increased in the order mode 1, mode 2 and mode 3, i.e.

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6962763B2 (en) 2004-02-25 2005-11-08 Eastman Kodak Company Silver-free black-and-white thermographic materials
US7022441B2 (en) 2004-02-25 2006-04-04 Eastman Kodak Company Silver-free black-and-white thermographic materials containing a benzoquinone and methods of imaging

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0692733A2 (fr) * 1994-07-07 1996-01-17 Agfa-Gevaert N.V. Procédé directe pour l'enregistrement thermique
EP0779539A1 (fr) * 1995-11-27 1997-06-18 Agfa-Gevaert N.V. Matériau thermographique avec une couche organique antistatique à l'extérieure
EP0903625A1 (fr) * 1997-09-17 1999-03-24 Agfa-Gevaert N.V. Nouveaux agents réducteurs pour l'utilisation en matériaux d'enregistrements thermographiques
US5922528A (en) * 1998-03-20 1999-07-13 Eastman Kodak Company Thermographic imaging element
EP1059560A1 (fr) * 1999-06-04 2000-12-13 Agfa-Gevaert N.V. Matériau thermographique d'enregistrement avec ton de l'image amélioré

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0692733A2 (fr) * 1994-07-07 1996-01-17 Agfa-Gevaert N.V. Procédé directe pour l'enregistrement thermique
EP0779539A1 (fr) * 1995-11-27 1997-06-18 Agfa-Gevaert N.V. Matériau thermographique avec une couche organique antistatique à l'extérieure
EP0903625A1 (fr) * 1997-09-17 1999-03-24 Agfa-Gevaert N.V. Nouveaux agents réducteurs pour l'utilisation en matériaux d'enregistrements thermographiques
US5922528A (en) * 1998-03-20 1999-07-13 Eastman Kodak Company Thermographic imaging element
EP1059560A1 (fr) * 1999-06-04 2000-12-13 Agfa-Gevaert N.V. Matériau thermographique d'enregistrement avec ton de l'image amélioré

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6962763B2 (en) 2004-02-25 2005-11-08 Eastman Kodak Company Silver-free black-and-white thermographic materials
US7022441B2 (en) 2004-02-25 2006-04-04 Eastman Kodak Company Silver-free black-and-white thermographic materials containing a benzoquinone and methods of imaging

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