EP1211093A1 - Thermographisches Aufzeichnungsmaterial mit verbessertem Bildton - Google Patents

Thermographisches Aufzeichnungsmaterial mit verbessertem Bildton Download PDF

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Publication number
EP1211093A1
EP1211093A1 EP01000630A EP01000630A EP1211093A1 EP 1211093 A1 EP1211093 A1 EP 1211093A1 EP 01000630 A EP01000630 A EP 01000630A EP 01000630 A EP01000630 A EP 01000630A EP 1211093 A1 EP1211093 A1 EP 1211093A1
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EP
European Patent Office
Prior art keywords
recording material
thermographic recording
substantially light
insensitive
image tone
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Withdrawn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
EP01000630A
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English (en)
French (fr)
Inventor
Johan c/o Agfa-Gevaert Loccufier
Ivan c/o AGFA-GEVAERT Hoogmartens
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
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Agfa Gevaert NV, Agfa Gevaert AG filed Critical Agfa Gevaert NV
Priority to EP01000630A priority Critical patent/EP1211093A1/de
Publication of EP1211093A1 publication Critical patent/EP1211093A1/de
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
    • B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers
    • B41M5/337—Additives; Binders
    • B41M5/3375—Non-macromolecular compounds
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/494—Silver salt compositions other than silver halide emulsions; Photothermographic systems ; Thermographic systems using noble metal compounds
    • G03C1/498—Photothermographic systems, e.g. dry silver
    • G03C1/49836—Additives
    • G03C1/49845—Active additives, e.g. toners, stabilisers, sensitisers
    • 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
    • B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers

Definitions

  • the present invention relates to thermographic recording materials whose prints have improved shelf-life image tone stability.
  • 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.
  • US 3,218,166 discloses a heat-sensitive copy sheet product capable of providing high contrast dense black images on a white background when briefly heated at image areas to conversion temperature within the approximate range of 90-150°C, said product containing, uniformly applied over a paperlike carrier and in position for heat-induced inter-reaction, reactants comprising a silver soap of an organic acid, a toner for the silver image, a ditertiaryalkyl substituted phenol first reducing agent for the silver ion in an amount of at least about 0.01 mol per mol of silver soap and insufficient to form with said silver soap a dense image when briefly heated therewith, and a photosensitive different active-hydrogen aromatic organic second reducing agent for said silver ion in an amount no greater than that of said first reducing agent, said first reducing agent being further characterized as forming with an equal weight of silver behenate and one-fifth said weight of phthalazinone a uniformly blended trace deposit requiring at least six seconds preheat at 100°C, before rapidly darkening at
  • US 3,547,648 discloses sheet material in copying processes, including a reactant layer comprising a silver soap of an organic acid, a tertiary-alkyl-substituted monophenol, and a tertiaryalkyl-substituted bisphenol, said substituted phenols each being a reducing agent for the silver ion and being characterized as forming with an equal weight of silver behenate and one fifth said weight of phthalazinone a uniformly blended trace deposit requiring at least six seconds preheat at 100°C before rapidly darkening at that temperature.
  • thermographic element comprising a support bearing at least one, image-forming, thermographic emulsion layer comprising: (a) a non-photosensitive, reducible silver source; (b) a reducing agent system for silver ion; and (c) a binder; wherein said reducing agent system comprises: (i) at least one hindered phenol; and (ii) at least one co-developer of the formula wherein: R represents an aromatic group or an electron withdrawing group.
  • ingredients are required for substantially light-insensitive thermographic recording materials, which provide a balance of image tone stabilizing properties, enabling prints to be obtained with image tone which after pretempering is less dependent upon storage time prior to printing and to archival time after printing, while exhibiting image tone acceptable for radiologists viewing images in transmission on a light box.
  • thermographic recording materials with improved image tone stability not only capable of producing prints with image tone which is less dependent upon storage time prior to printing.
  • thermographic recording materials comprising a thermosensitive element containing sterically hindered monophenols are capable of providing prints whose image tone is less dependent upon storage time prior to printing than prior art materials substantially light-insensitive thermographic recording materials.
  • thermosensitive black and white thermographic recording material comprising a support and a thermosensitive element exclusive of bisphenol compounds, 4-substituted isoxazole compounds of the formula wherein R represents an aromatic group or an electron withdrawing group, organic compounds represented by R 3 -H, the corresponding radical of which, R 3• , has a stability of from 350 to 6000 times that of a primary alkyl radical, and photosensitive active-hydrogen aromatic organic reducing agents, the thermosensitive element containing at least one substantially light-insensitive organic silver salt, an organic reducing agent therefor in thermal working relationship therewith, an image tone stabilizer and a binder, characterized in that the image tone stabilizer is a sterically hindered monophenol.
  • thermographic recording material as described above into proximity with a heat source; (ii) applying heat from the heat source imagewise to the thermographic recording material in a substantially water-free condition while maintaining proximity to the heat source to produce an image; and (iii) removing the thermographic recording material from the heat source.
  • thermographic recording material Use of a sterically hindered monophenol in a substantially light-insensitive thermographic recording material as an image tone stabilizer is also provided by the present invention.
  • the heat source is a thermal head.
  • the heat source is a thin film thermal head.
  • 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.
  • substantially light-insensitive is meant not intentionally light sensitive.
  • ortho to the hydroxy group is meant covalently bonded to the carbon atoms immediately adjacent to the carbon atom to which the hydroxy group is covalently bonded.
  • a fatty acid is an organic monobasic acid of general formula C n H 2n + 1 COOH derived from the saturated series of aliphatic hydrocarbons, such as palmitic acid, stearic acid, behenic acid and arichidic acid.
  • Heating in a 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.
  • thermographic recording material comprising a support and a thermosensitive element of bisphenol compounds, 4-substituted isoxazole compounds of the formula wherein R represents an aromatic group or an electron withdrawing group, organic compounds represented by R 3 -H, the corresponding radical of which, R 3• , has a stability of from 350 to 6000 times that of a primary alkyl radical, and photosensitive active-hydrogen aromatic organic reducing agents, the thermosensitive element containing at least one substantially light-insensitive organic silver salt, an organic reducing agent therefor in thermal working relationship therewith, an image tone stabilizer and a binder, characterized in that the image tone stabilizer is a sterically hindered monophenol.
  • the sterically hindering groups in the sterically hindered monophenol are alkyl and cycloalkyl groups ortho to the hydroxy group.
  • the sterically hindering groups in the sterically hindered monophenol ortho to the hydroxy group are selected from the group consisting of optionally substituted isopropyl, tertiary butyl, isobutyl, tertiary octyl, cyclopentyl and cyclohexyl groups.
  • the sterically hindered monophenol has substituents other than the sterically hindering groups ortho to the hydroxy group selected from the group consisting of optionally substituted alkyl, cycloalkyl, alkoxy, aryloxy, carboxy and carboxyalkyl groups.
  • Suitable image tone stabilizing compounds according to the present invention are:
  • the image tone stabilizer is 3,5-di-tert-butyl-4-hydroxybenzoic acid (ITS-1).
  • thermosensitive element as used herein is that element which contains all the ingredients which contribute to image formation.
  • the thermosensitive element is exclusive of bisphenol compounds, 4-substituted isoxazole compounds of the formula wherein R represents an aromatic group or an electron withdrawing group, organic compounds represented by R 3 -H, the corresponding radical of which, R 3• , has a stability of from 350 to 6000 times that of a primary alkyl radical, and photosensitive active-hydrogen aromatic organic reducing agents.
  • the thermosensitive contains a substantially light-insensitive organic silver salt, an organic reducing agent therefor in thermal working relationship therewith, a sterically hindered phenol image tone stabilizer and a binder.
  • thermosensitive element is exclusive of 4-substituted isoxazole compounds.
  • thermosensitive element is exclusive of hydrogen atom donor compounds.
  • thermosensitive element is exclusive of hydrazide compounds.
  • the thermosensitive element comprises 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 salt is in reactive association with the reducing agent 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 substantially light-insensitive organic silver salt is a substantially light-insensitive silver salt of an organic carboxylic acid.
  • the substantially light-insensitive silver salt is a silver salt of an aliphatic carboxylic acid.
  • the substantially light-insensitive silver salt is a silver salt of a fatty acid.
  • the substantially light-insensitive silver salt is a silver salt of an aliphatic carboxylic acid, wherein the aliphatic carbon chain has between 12 and 30 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".
  • the substantially light-insensitive silver salt is an organic carboxylic acid as described in GB-P 1,439,478, e.g. silver benzoate.
  • Combinations of different silver salts of an organic carboxylic acids may also be used in the present invention, as disclosed in EP-A 964 300, hereby incorporated by reference.
  • Organic silver salts may be dispersed by standard dispersion techniques e.g. using 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 a more finely ground dispersions of organic silver salts.
  • the organic reducing agent for the reduction of the substantially light-insensitive organic silver salt is an organic compound containing at least one active hydrogen atom linked to O, N or C, such as is the case with, aromatic di- and tri-hydroxy compounds.
  • the organic reducing agent is a 1,2-dihydroxybenzene derivative, such as catechol, 3-(3,4-dihydroxyphenyl) propionic acid, 1,2-dihydroxybenzoic acid, gallic acid and esters e.g. methyl gallate, ethyl gallate, propyl gallate, tannic acid, and 3,4-dihydroxy-benzoic acid ester.
  • 1,2-dihydroxybenzene derivative such as catechol, 3-(3,4-dihydroxyphenyl) propionic acid, 1,2-dihydroxybenzoic acid, gallic acid and esters e.g. methyl gallate, ethyl gallate, propyl gallate, tannic acid, and 3,4-dihydroxy-benzoic acid ester.
  • the organic reducing agent is an organic reducing agent disclosed in EP-B 692 733, herein incorporated by reference, e.g. ethyl 3,4-dihydroxybenzoate and n-butyl 3,4-dihydroxybenzoate,
  • thermographic recording material is an organic reducing agent disclosed in EP-A 903 625, herein incorporated by reference, e.g. 3,4-dihydroxybenzonitrile.
  • Combinations of reducing agents may also be used that on heating become reactive partners in the reduction of the substantially light-insensitive organic silver salt containing mixed crystals of two or more organic silver salts.
  • combinations of sterically hindered phenols with sulfonyl hydrazide reducing agents such as disclosed in US-P 5,464,738; trityl hydrazides and formyl-phenyl-hydrazides such as disclosed in US-P 5,496,695; trityl hydrazides and formyl-phenyl-hydrazides with diverse auxiliary reducing agents such as disclosed in US-P 5,545,505, US-P 5.545.507 and US-P 5,558,983; acrylonitrile compounds as disclosed in US-P 5,545,515 and US-P 5,635,339; and 2-substituted malonodialdehyde compounds as disclosed in US-P 5,654,130.
  • thermosensitive element Binder of the thermosensitive element
  • the binder is a natural, modified natural or synthetic resins or mixtures of such resins, in which the substantially light-insensitive organic silver salt can be homogeneously dispersed 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 binder is a water-soluble film-forming binder, for example: polyvinyl alcohol, polyacrylamide, polymethacrylamide, polyacrylic acid, polymethacrylic acid, polyvinylpyrrolidone, polyethyleneglycol, proteinaceous binders such as gelatine, modified gelatines such as phthaloyl gelatine, polysaccharides, such as starch, gum arabic and dextran and water-soluble cellulose derivatives.
  • a water-soluble film-forming binder for example: polyvinyl alcohol, polyacrylamide, polymethacrylamide, polyacrylic acid, polymethacrylic acid, polyvinylpyrrolidone, polyethyleneglycol, proteinaceous binders such as gelatine, modified gelatines such as phthaloyl gelatine, polysaccharides, such as starch, gum arabic and dextran and water-soluble cellulose derivatives.
  • the binder is gelatin.
  • the weight ratio of binder to substantially light-insensitive organic silver salt is in the range of 0.2 to 7.
  • the thickness of the thermosensitive element is in the range of 5 to 50 ⁇ m.
  • the binder does not contain additives or impurities which adversely affect the thermographic properties of the substantially thermographic recording material.
  • thermosensitive element further contains a toning agent in order to obtain a neutral black image tone in the higher densities and neutral grey in the lower densities.
  • the thermosensitive element further contains at least one toning agent selected from the group consisting of phthalimides and phthalazinones.
  • Suitable toning agents are those within the scope of the general formulae described in US 4,082,901. Further reference is made to the toning agents described in US 3,074,809, 3,446,648 and 3,844,797.
  • the thermosensitive element contains at least one heterocyclic toning compounds of the benzoxazine dione or naphthoxazine dione type as disclosed in GB 1,439,478, US 3,951,660, e.g. benzo[e][1,3]oxazine-2,4-dione and 7-methyl-benzo[e][1,3]oxazine-2,4-dione, and US 5,599,647, e.g. 7-(ethylcarbonato)-benzo[e][1,3]oxazine-2,4-dione, herein incorporated by reference.
  • the substantially light-insensitive thermographic recording material further contains an antifoggant to obtain improved shelf-life and reduced fogging.
  • the substantially light-insensitive thermographic recording material further contains at least one antifoggant 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.
  • at least one antifoggant 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
  • the thermosensitive element further comprises at least one 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 thermosensitive element further comprises at least one aliphatic (saturated as well as unsaturated aliphatic and also cycloaliphatic) or aromatic polycarboxylic acid, optionally substituted and optionally 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.
  • at least one aliphatic (saturated as well as unsaturated aliphatic and also cycloaliphatic) or aromatic polycarboxylic acid optionally substituted and optionally 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.
  • Surfactants and dispersants aid the dispersion of ingredients or reactants which are insoluble in the particular dispersion medium.
  • the substantially light-insensitive thermographic recording material further comprises one or more surfactants, which may be anionic, non-ionic or cationic surfactants, and/or one or more dispersants.
  • 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 antistatic agents, e.g. non-ionic antistatic agents including a fluorocarbon group as e.g. in F 3 C(CF 2 ) 6 CONH(CH 2 CH 2 O)-H, silicone oil, e.g. BAYSILONTM MA (from BAYER AG, GERMANY).
  • antistatic agents e.g. non-ionic antistatic agents including a fluorocarbon group as e.g. in F 3 C(CF 2 ) 6 CONH(CH 2 CH 2 O)-H
  • silicone oil e.g. 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 a solvent-soluble polycarbonate binder as described in EP-A 614 769, herein incorporated by reference.
  • the thermosensitive element is provided with a protective layer comprising a water-soluble or water-dispersible binders, 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.
  • thermosensitive element is provided with a crosslinked protective layer.
  • thermosensitive element is provided with a protective layer crosslinked with crosslinking agents such as described in WO 95/12495, herein incorporated by reference.
  • thermosensitive element is provided with a protective layer comprising solid or liquid lubricants or combinations thereof for improving the slip characteristics of the substantially light-insensitive thermographic recording material.
  • thermosensitive element is provided with a protective layer comprising thermomeltable particles as solid lubricants are thermomeltable particles, such as those described in WO 94/11199, herein incorporated by reference.
  • the thermosensitive element is provided with a protective layer comprising a matting agent, such as described in WO 94/11198, herein incorporated by reference, e.g. talc particles, which optionally protrude from the protective layer.
  • a matting agent such as described in WO 94/11198, herein incorporated by reference, e.g. talc particles, which optionally protrude from the protective layer.
  • 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.
  • 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.
  • the silver behenate dispersion was produced as follows: 25kg (73.5M) behenic acid was dispersed with stirring at 80°C in 100L of a 10% solution of Surfactant Nr. 1 per g behenic acid made up to 250L with deionized water at a temperature of 80°C; then 36.75L of a 2M aqueous solution of sodium hydroxide was added over a period of 10 to 20 minutes to give a clear solution substantially containing sodium behenate; then 25L of a 2.94M aqueous solution of silver nitrate was added with stirring at a rate of 0.163 moles/moles silver behenate ⁇ min to convert the sodium behenate completely into silver behenate; and finally ultrafiltration was carried out with a 500000 MW polysulfone cartridge filter at room temperature to concentrate the resulting silver behenate dispersion while adding ammonium nitrate to convert Surfactant Nr 1 into its ammonium salt, the final AgBeh-concentration was 20.4% with 0.062g
  • thermographic recording materials Preparation of thermographic recording materials
  • the coating dispersion for the thermosensitive element was produced by first allowing 3.44g of K17881 to swell in 16.33g of deionized water over a period of 30 minutes. 3.05g of a first aqueous toning agent dispersion containing 18.08% of T01 and 9.95% of K17881 and 0.8g of a second toning agent dispersion containing 20.12% of T02 and 8.88% of R16875 were then added and the resulting dispersion heated with stirring up to 50°C.
  • This coating dispersion at a temperature of 36°C was then doctor-blade coated onto the non-backing layer side of a subbed 168 ⁇ m thick blue-pigmented polyethylene terephthalate support with a backing layer (optical density upon measurement with a MACBETHTM TR924 densitometer through visible and blue filters in transmission of subbed support with backing layer was 0.19 and 0.05 respectively) to a wet coating weight of 72 g/m 2 and while undried was overcoated with 11g/m 2 of an aqueous solution with 1.8% by weight of 1,1-bis(vinylsulfono)methane and 0.9091% by weight of Surfactant Nr. 1.
  • thermosensitive elements of COMPARATIVE EXAMPLE 1 and INVENTION EXAMPLE 1 were obtained.
  • thermographic printing of the substantially light-insensitive thermographic recording materials of COMPARATIVE EXAMPLE 1 and INVENTION EXAMPLE 1 the print head was separated from the imaging layer by a thin intermediate material contacted with a slipping layer of a separable 5 ⁇ m thick polyethylene terephthalate ribbon coated successively with a subbing layer, heat-resistant layer and the slipping layer (anti-friction layer) giving a ribbon with a total thickness of 6 ⁇ m.
  • the DRYSTAR® 2000 printer from AGFA-GEVAERT was equipped with a thin film thermal head with a resolution of 300 dpi and was operated with a line time of 11.8ms (the line time being the time needed for printing one line). During this line time the print head received constant power. The printing power was 90mW and the thermal head resistors were time-modulated to produce different image densities.
  • the image tone of fresh prints made with the substantially light-insensitive thermographic recording materials of COMPARATIVE EXAMPLE 1 and INVENTION EXAMPLE 1 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 a* and b* CIELAB-values of fresh prints of the substantially light-insensitive thermographic recording materials of COMPARATIVE EXAMPLE 1 and INVENTION EXAMPLE 1 at optical densities, D, of 1.0 are also given in Table 2.
  • 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 of INVENTION EXAMPLE 1 after 3 days at 45°C and 70% relative humidity have a CIELAB b* value which is more blue at a density of 1.0 i.e. b* is negative and closer to the desired level for b* of - 8.8, as can be seen from Table 3 above.
  • thermographic recording materials incorporating sterically hindered monophenols as image tone stabilizing compounds exhibit an improved shelf-life image tone stability over substantially light-insensitive thermographic recording materials without sterically hindered monophenols.

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EP01000630A 2000-11-30 2001-11-14 Thermographisches Aufzeichnungsmaterial mit verbessertem Bildton Withdrawn EP1211093A1 (de)

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EP1388753A1 (de) * 2002-08-09 2004-02-11 Eastman Kodak Company Wärmeentwickelbare Emulsionen und Bildaufzeichnungsmaterialien, die eine Bindemittelmischung enthalten
WO2007010777A1 (ja) 2005-07-20 2007-01-25 Konica Minolta Medical & Graphic, Inc. 画像形成方法
EP1953592A1 (de) 2007-02-02 2008-08-06 Konica Minolta Medical & Graphic, Inc. Photothermographisches Material
EP1557669B1 (de) * 2004-01-14 2014-09-24 FUJIFILM Corporation Verwendung eines Gas Sensormaterials und Verfahren zum Nachweis von Gas

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WO1997011407A1 (en) * 1995-09-19 1997-03-27 Imation Corp. Black-and-white photothermographic and thermographic elements comprising hydrogen atom donor compounds as contrast enhancers
WO1997034196A1 (en) * 1996-03-14 1997-09-18 Imation Corp. Black-and-white photothermographic and thermographic elements comprising 4-substituted isoxazole compounds as co-developers

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US3218166A (en) * 1962-11-23 1965-11-16 Minnesota Mining & Mfg Heat sensitive copy sheet
US3547648A (en) * 1968-01-26 1970-12-15 Minnesota Mining & Mfg Copy-sheet
GB1410991A (en) * 1972-06-13 1975-10-22 Agfa Gevaert Method and materials for thermographic recording
US4013473A (en) * 1974-08-24 1977-03-22 Agfa-Gevaert N.V. Recording materials and image receiving materials for producing copies in a dry way
WO1997011407A1 (en) * 1995-09-19 1997-03-27 Imation Corp. Black-and-white photothermographic and thermographic elements comprising hydrogen atom donor compounds as contrast enhancers
WO1997034196A1 (en) * 1996-03-14 1997-09-18 Imation Corp. Black-and-white photothermographic and thermographic elements comprising 4-substituted isoxazole compounds as co-developers

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1388753A1 (de) * 2002-08-09 2004-02-11 Eastman Kodak Company Wärmeentwickelbare Emulsionen und Bildaufzeichnungsmaterialien, die eine Bindemittelmischung enthalten
EP1557669B1 (de) * 2004-01-14 2014-09-24 FUJIFILM Corporation Verwendung eines Gas Sensormaterials und Verfahren zum Nachweis von Gas
WO2007010777A1 (ja) 2005-07-20 2007-01-25 Konica Minolta Medical & Graphic, Inc. 画像形成方法
EP1953592A1 (de) 2007-02-02 2008-08-06 Konica Minolta Medical & Graphic, Inc. Photothermographisches Material

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