EP0903623A1 - Bindemittel für thermographische Materialien - Google Patents

Bindemittel für thermographische Materialien Download PDF

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Publication number
EP0903623A1
EP0903623A1 EP98202543A EP98202543A EP0903623A1 EP 0903623 A1 EP0903623 A1 EP 0903623A1 EP 98202543 A EP98202543 A EP 98202543A EP 98202543 A EP98202543 A EP 98202543A EP 0903623 A1 EP0903623 A1 EP 0903623A1
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EP
European Patent Office
Prior art keywords
substantially light
insensitive
water
covalently bonded
thermographic material
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EP98202543A
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English (en)
French (fr)
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EP0903623B1 (de
Inventor
Frank Louwet
Huub Van Aert
Frank Ruttens
Ivan Hoogmartens
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Agfa Gevaert NV
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Agfa Gevaert NV
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Priority to EP19980202543 priority Critical patent/EP0903623B1/de
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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 substantially light-insensitive black and white thermographic material comprising a thermosensitive element including a binder having covalently bonded ionic groups.
  • Thermal imaging or thermography is a recording process wherein images are generated by the use of thermal energy.
  • thermography three approaches are known:
  • thermographic recording materials are of the chemical type. On heating to a certain conversion temperature, an irreversible chemical reaction takes place and a coloured image is produced.
  • a wide variety of chemical systems has been suggested some examples of which have been given on page 138 of "Imaging Systems” by Kurt I. Jacobson-Ralph E. Jacobson, The Focal Press - London and New York (1976), describing the production of a silver metal image by means of a thermally induced oxidation-reduction reaction of a silver soap with a reducing agent.
  • DE 3635441 discloses a process for producing an image, characterized in that a thermally developable photosensitive material, comprising a support with at least a photosensitive silver halide and a high molecular weight compound containing a repeating unit derived from a vinyl monomer with a -COOM-group and/or a -SO 3 M-group, wherein M represents a hydrogen atom or an alkali metal atom, is heated, simultaneously or after image-wise exposure, in the presence of water and at least a base and/or a base-precursor.
  • JP 61-193142 discloses a heat development photosensitive material characterized in that in thermally developed photosensitive material which has a photosensitive layer containing at least silver halide particles on a support, the said photosensitive material has a layer which contains a water soluble or water dispersible block copolymer which has a polyvinyl alcohol system polymer as one component and a polymer which has an ionic group as the other component.
  • EP 678 776 discloses a thermally processable imaging element, said element comprising: (1) a support; and (2) a thermographic or photothermographic imaging layer on one side of said support; characterized in that said element additionally comprises (3) at least one electroconductive outermost layer comprised of electrically-conductive metal-containing particles dispersed in a polymeric binder in an amount sufficient to provide a surface resistivity of less than 5 x 10 11 ohms/square.
  • thermographic materials based on organic silver salts and reducing agents.
  • WO 94/16361 discloses a multilayer heat-sensitive material which comprises: a colour-forming layer comprising: a colour-forming amount of finely divided, solid colourless noble metal or iron salt of an organic acid distributed in a carrier composition; a colour developing amount of a cyclic or aromatic organic reducing agent, which at thermal copy and printing temperatures is capable of a colour-forming reaction with the noble metal or iron salt; and an image-toning agent; characterized in that (a) the carrier composition comprises a substantially water-soluble polymeric carrier and a dispersing agent for the noble metal or iron salt and (b) the material comprises a protective overcoating layer for the colour-forming layer.
  • WO 94/16361 the following water-soluble polymeric carriers: polyvinyl alcohol, methyl cellulose, carboxy methyl cellulose, polysaccharide gums, gelatins, styrene butadiene copolymers, hydroxylated corn starch, acrylic latexes and blends and mixtures thereof.
  • dispersing agent the ammonium salt of styrene/acrylic acid is recited, with LUPASOLTM FF-3249 from BASF being used in the invention examples.
  • thermographic materials containing conventional acrylic latexes coated from aqueous media exhibited poor archivability and poor light stability.
  • thermographic materials coated from aqueous media which exhibit improved archivability and/or improved light stability, while maintaining high maximum density and low minimum density levels upon printing.
  • thermographic materials coated from an aqueous medium exhibit substantially improved archivability and increased light stability upon using water-dispersible film-forming polymers with covalently bonded ionic groups instead of the conventional acrylic latexes disclosed for this purpose in WO 94/16361.
  • thermographic material including a support and a thermosensitive element, containing a substantially light-insensitive organic silver salt, a reducing agent therefor in thermal working relationship therewith and a binder, characterized in that the binder is a water-dispersible film-forming polymer having covalently bonded ionic groups and the thermographic material is thermally developable under substantially water-free conditions.
  • a process for producing the substantially light-insensitive black and white thermographic material referred to above comprising the steps of: producing an aqueous dispersion of the substantially light-insensitive organic silver salt; producing one or more aqueous coating compositions containing together the aqueous dispersion of the substantially light-insensitive organic silver salt, the reducing agent and the binder; and applying the one or more aqueous coating compositions to the support thereby forming after drying the thermosensitive element.
  • substantially light-insensitive is meant not intentionally light sensitive.
  • thermally developable under substantially water-free conditions means heating at a temperature of 80° to 250°C under conditions in which 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 of the thermographic recording material.
  • a condition is described in T. H. James, "The Theory of the Photographic Process, Fourth Edition, Macmillan 1977, page 374.
  • aqueous for the purposes of the present invention includes mixtures of water with water-miscible organic solvents such as alcohols e.g. methanol, ethanol, 2-propanol, butanol, iso-amyl alcohol, octanol, cetyl alcohol etc.; glycols e.g. ethylene glycol; glycerine; N-methyl pyrrolidone; methoxypropanol; and ketones e.g. 2-propanone and 2-butanone etc.
  • alcohols e.g. methanol, ethanol, 2-propanol, butanol, iso-amyl alcohol, octanol, cetyl alcohol etc.
  • glycols e.g. ethylene glycol
  • glycerine N-methyl pyrrolidone
  • methoxypropanol and ketones e.g. 2-propanone and 2-butanone etc.
  • the binder used according to the present invention is a water-dispersible film-forming polymer having covalently bonded ionic groups.
  • the water-dispersible film-forming polymer having covalently bonded ionic groups used in the present invention is preferably a copolymer of an ionic monomer with covalently bonded anionic or cationic groups, for example:
  • the water-dispersible film-forming polymer having covalently bonded ionic groups used according to the present invention preferably contains crosslinkable groups, for example: acetoacetoxy-groups, epoxy-groups and double bonds.
  • the water-dispersible film-forming polymer having covalently bonded ionic groups used according to the present invention is preferably a polymer latex.
  • the water-dispersible film-forming polymer having covalently bonded ionic groups used according to the present invention preferably has covalently bonded moieties with one or more acid groups or anhydrides thereof, which are preferably carboxylic acid groups, for example copolymers of acrylic acid, methacrylic acid, crotonic acid, itaconic acid, mesaconic acid, glutaconic acid, citraconic acid, acotinic acid, maleic acid, maleic anhydride and fumaric acid.
  • Particularly preferred covalently bonded moieties with one or more carboxylic acid groups or anhydrides thereof are copolymers having monomer units selected from the group consisting of itaconic acid, mesaconic acid, glutaconic acid, citraconic acid, aconitic acid, maleic acid, maleic anhydride and fumaric acid.
  • the covalently bonded ionic groups of the water-dispersible film-forming polymer used according to the present invention are preferably selected from the group consisting of sulfonate, sulfinate, carboxylate, phosphate, quaternary ammonium, tertiary sulfonium and quaternary phosphonium groups.
  • quaternary ammonium also includes heterocyclic quaternary ammonium groups for example pyridinium groups.
  • the water-dispersible film-forming polymer having covalently bonded ionic groups used according to the present invention preferably has monomer units selected from the group consisting of acrylates, methacrylates, styrene, diene monomers, vinyl esters, substituted vinyl esters, polycarboxylic acids, polyols and polyisocyanates.
  • binders which can be used according to the present invention are the CYDROTHANETM polyurethane dispersions from CYTEC listed in table 1, which are fully reacted, high molecular weight polyurethane-polyurea polymers dispersed in water by neutralizing the ionic groups in the prepolymer backbone.
  • the water-dispersible film forming polymer having covalently bonded ionic groups used according to the present invention may be used with additional water-soluble and/or water-dispersible binders.
  • Film-forming binders suitable for materials coated from solvent dispersions or solutions may be all kinds of natural, modified natural or synthetic resins or mixtures of such resins, wherein the organic silver salt can be dispersed homogeneously or dissolved.
  • Suitable water-soluble film-forming binders for use in thermographic materials according to the present invention are: polyvinyl alcohol, polyacrylamide, polyacrylic acid, polymethacrylic acid, polyvinylpyrrolidone, polyethyleneglycol, proteinaceous binders such as gelatin modified gelatins such as phthaloyl gelatin, polysaccharides, such as starch, gum arabic and dextran and water-soluble cellulose derivatives.
  • Suitable water-dispersible binders for use in the thermographic materials of the present invention may be any water-insoluble polymer e.g. water-insoluble cellulose derivatives, polyurethanes, polyesters and polymers derived from ⁇ , ⁇ -ethylenically unsaturated compounds such as after-chlorinated polyvinyl chloride, partially hydrolyzed polyvinyl acetate, polyvinyl alcohol, polyvinyl acetals preferably polyvinyl butyral, and homopolymers and copolymers produced using monomers selected from the group consisting of: vinyl chloride, vinylidene chloride, acrylonitrile, acrylamides, methacrylamides, methacrylates, acrylates, methacrylic acids, acrylic acids, vinyl esters, styrenes and alkenes; or mixtures thereof. It should be noted that there is no clear cut transition between a polymer dispersion and a polymer solution in the case of very small polymer particles resulting in the smallest
  • plasticizers can be incorporated into the polymers, water-miscible solvents can be added to the dispersion medium and mixtures of water-soluble polymers, mixtures of water-dispersible polymers, or mixtures of water-soluble and water-dispersible polymers may be used.
  • thermosensitive element of the present invention is gelatin.
  • binders or mixtures thereof may be used in conjunction with waxes or "heat solvents” also called “thermal solvents” or “thermosolvents” improving the reaction speed of the redox-reaction at elevated temperature.
  • heat solvent in this invention is meant a non-hydrolyzable organic material which is in a solid state in the recording layer at temperatures below 50°C, but upon heating becomes a plasticizer for the recording layer and/or a liquid solvent for at least one of the redox-reactants.
  • thermographic recording material comprising a thermosensitive element including a substantially light-insensitive organic silver salt, an organic reducing agent therefor in thermal working relationship therewith and a binder.
  • the element may comprise a layer system in which the ingredients are dispersed in different layers, with the proviso that the substantially light-insensitive organic silver salt and the organic reducing agent are in thermal working relationship with one another 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 substantially light-insensitive organic silver salt particles so that reduction of the organic silver salt can take place.
  • the thickness of the thermosensitive element is preferably in the range of 1 to 50 ⁇ m.
  • Preferred substantially light-insensitive organic silver salts used in the present invention are silver salts of organic carboxylic acids and in particular 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 salts of modified aliphatic carboxylic acids with thioether group as described e.g. in GB-P 1,111,492 and other organic silver salts as described in GB-P 1,439,478, e.g.
  • silver benzoate may likewise be used to produce a thermally developable silver image.
  • Combinations of different organic silver salts may also be used in the present invention.
  • a process for producing a suspension of particles containing a substantially light-insensitive organic silver salt is disclosed in EP-A 754 969.
  • the weight ratio of binder used according to the present invention to organic silver salt weight is preferably in the range of 0.2 to 6.
  • Suitable organic reducing agents for the reduction of the substantially light-insensitive organic silver salts are organic compounds containing at least one active hydrogen atom linked to O, N or C, such as is the case with: catechol; hydroquinone; aminophenols; METOLTM; p-phenylenediamines; alkoxynaphthols, e.g. 4-methoxy-1-naphthol described in US-P 3,094,417; pyrazolidin-3-one type reducing agents, e.g.
  • PHENIDONETM pyrazolin-5-ones; indan-1,3-dione derivatives; hydroxytetrone acids; hydroxytetronimides; hydroxylamine derivatives such as for example described in US-P 4,082,901; hydrazine derivatives; and reductones e.g. ascorbic acid; see also US-P 3,074,809, 3,080,254, 3,094,417 and 3,887,378.
  • auxiliary reducing agents are e.g. sterically hindered phenols, such as described in US-P 4,001,026; bisphenols, e.g. of the type described in US-P 3,547,648; or sulfonamidophenols as described in Research Disclosure 17842 published in February 1979, US-P 4,360,581, US-P 4,782,004 and in EP-A 423 891.
  • the auxiliary reducing agents may be present in the imaging layer or in a polymeric binder layer in thermal working relationship thereto.
  • auxiliary reducing agents that may be used in conjunction with the above mentioned primary reducing agents are hydrazides such as disclosed in EP-A 762 196, 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; 2-substituted malondialdehyde compounds as disclosed in US-P 5,654,130; and organic reducing metal salts, e.g. stannous stearate described in US-P 3,460,946 and 3,547,648.
  • thermographic recording materials may contain one or more toning agents.
  • the toning agents should be in thermal working relationship with the substantially light-insensitive organic silver salt and reducing agents during thermal processing. Any known toning agent from thermography or photothermography may be used. Suitable toning agents are the phthalimides and phthalazinones within the scope of the general formulae described in US-P 4,082,901 and the toning agents described in US-P 3,074,809, US-P 3,446,648 and US-P 3,844,797.
  • Particularly useful toning agents are the heterocyclic toner compounds of the benzoxazine dione or naphthoxazine dione type described in GB-P 1,439,478, US-P 3,951,660 and US-P 5,599,647.
  • 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.
  • Suitable surfactants are:
  • Suitable dispersants are natural polymeric substances, synthetic polymeric substances and finely divided powders, for example finely divided non-metallic inorganic powders such as silica.
  • thermographic recording materials of the present invention is the possibility of reducing the concentration of dispersion aids in the thermosensitive element, due to the use of water-dispersible film-forming polymers having covalently bonded ionic groups.
  • stabilizers and antifoggants may be incorporated into the thermographic and photothermographic materials of the present invention.
  • thermographic material may contain other additives such as free fatty acids, silicone oil, ultraviolet light absorbing compounds, white light reflecting and/or ultraviolet radiation reflecting pigments, silica, and/or optical brightening agents.
  • the support for the thermographic material according to the present invention may be transparent, translucent or opaque and 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 needs be to improve the adherence to the thereon coated heat-sensitive recording layer.
  • the support may be made of an opacified resin composition.
  • thermosensitive element may also be provided for the thermosensitive element. In general this protects the thermosensitive element from atmospheric humidity and from surface damage by scratching etc. and prevents direct contact of printheads or heat sources with the recording layers. Protective layers for thermosensitive elements which come into contact with and have to be transported past a heat source under pressure, have to exhibit resistance to local deformation and good slipping characteristics during transport past the heat source during heating.
  • the protective layer may comprise a dissolved lubricating material and/or particulate material, e.g. talc particles, optionally protruding therefrom.
  • suitable lubricating materials are a surface active agent, a liquid lubricant, a solid lubricant or mixtures thereof, which may be used with or without a polymeric binder.
  • Suitable slipping layer compositions are described, for example, in US 5,587,350, US 5,536,696, US 5,547,914, WO 95/12495, EP-A 775 592 and EP-A 775 595.
  • thermographic materials 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, USA.
  • Thermographic imaging is carried out by the image-wise application of heat either in analogue fashion by direct exposure through an image of 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, 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 via the Joule effect into heat, which is transferred to the surface of the thermographic material wherein the chemical reaction resulting in the development of a black and white image takes place.
  • Such thermal printing heads may be used in contact or close proximity with the recording layer.
  • 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 1.0 ms, 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 layer 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.
  • the image signals for modulating the laser beam or current in the micro-resistors of a thermal printhead are obtained directly e.g. from opto-electronic scanning devices or from an intermediary storage means, e.g. magnetic disc or tape or optical disc storage medium, optionally linked to a digital image work station wherein the image information can be processed to satisfy particular needs.
  • an intermediary storage means e.g. magnetic disc or tape or optical disc storage medium
  • thermographic material can be not suitable for reproducing images with fairly large number of grey levels as is required for continuous tone reproduction.
  • 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 thermographic material can also be carried out using an electrically resistive ribbon incorporated into the material.
  • Image- or pattern-wise heating of the thermographic material may also proceed by means of pixelwise modulated ultra-sound, using e.g. an ultrasonic pixel printer as described e.g. in US-P 4,908,631.
  • Thermographic materials according to the present invention may be used for both the production of transparencies, for example in the medical diagnostic field in which black-imaged transparencies are widely used in inspection techniques operating with a light box, and reflection type prints, for example in the hard copy field.
  • the support will be transparent or opaque, i.e. having a white light reflecting aspect.
  • the base may be colourless or coloured, e.g. with a blue colour for medical diagnostic applications.
  • thermosensitive element ingredients ii) thermosensitive element ingredients:
  • dispersant nr 1 71.5g of dispersant nr 1, 187.5g of a 10% aqueous solution of Surfactant nr 5 and 1741g of deionized water were well mixed and then 500g of silver behenate powder was added with stirring with a HOMOREXTM stirrer. Stirring was continued for 15 minutes after the addition of the silver behenate and then the resulting dispersion was stored for 24 hours in a refrigerator to allow the foam to dissipate. The dispersion was then stirred for 10 minutes with an ULTRA-TURRAXTM stirrer and then passed once through a MICROFLUIDICSTM microfluidizer at a pressure of 400 bar to obtain the final dispersion.
  • the coating dispersion was prepared by adding with stirring to the latex dispersion (for polymer latex number, quantity and concentration see table 5 and for surfactants present in the latex dispersion including those added during the preparation of the coating dispersion see table 7): 26.35g of the 20% silver behenate dispersion at 40°C, deionized water (for quantity see table 5) and finally a 9.4% aqueous solution of Surfactant Nr. 3 (for quantity see table 5 and for surfactants present in the coating dispersion both from the latex dispersion and added during the preparation of the coating dispersion see table 7).
  • the silver behenate emulsion layers were overcoated with a solution containing 2.64g of K7598, 0.65g of R01 (catechol) dissolved in 61.05g of deionized water to which 0.3g of a 1.4% solution of surfactant nr. 4 had been added to a R01 coating weight of 0.65g/m 2 after drying for 10 minutes at 50°C.
  • the printer was equipped with a thin film thermal head with a resolution of 300 dpi and was operated with a line time of 19ms (the line time being the time needed for printing one line). During this line time the printhead received constant power.
  • the average printing power being the total amount of electrical input energy during one line time divided by the line time and by the surface area of the heat-generating resistors was 1.6 mJ/dot, being sufficient to obtain maximum optical density in each of the thermographic materials of COMPARATIVE EXAMPLES 1 to 6 and INVENTION EXAMPLES 1 to 4.
  • the maximum densities, D max , and minimum densities, D min , of the prints given in table 3 were measured through a blue filter with a MACBETHTM TR924 densitometer in the grey scale steps corresponding to data levels of 255 and 0 respectively and are given in table 7.
  • the stability of the image background of the prints made with the thermographic materials of COMPARATIVE EXAMPLES 1 to 6 and INVENTION EXAMPLES 1 to 4 was evaluated on the basis of the change in minimum (background) density measured through a blue filter using a MACBETHTM TR924 densitometer upon exposure on top of the white PVC window of a specially constructed light-box placed for 3 days in a VOTSCH conditioning cupboard set at 30°C and a relative humidity (RH) of 85%. Only a central area of the window 550mm long by 500mm wide was used for mounting the test materials to ensure uniform exposure.
  • the stainless steel light-box used was 650mm long, 600mm wide and 120mm high with an opening 610mm long and 560mm wide with a rim 10mm wide and 5mm deep round the opening, thereby forming a platform for a 5mm thick plate of white PVC 630mm long and 580mm wider, making the white PVC-plate flush with the top of the light-box and preventing light loss from the light-box other than through the white PVC-plate.
  • This light-box was fitted with 9 PLANILUXTM TLD 36W/54 fluorescent lamps 27mm in diameter mounted length-wise equidistantly from the two sides, with the lamps positioned equidistantly to one another and the sides over the whole width of the light-box and with the tops of the fluorescent tubes 30mm below the bottom of the white PVC plate and 35mm below the materials being tested.
  • Table 7 Comparative Example Nr AgBeh coverage [g/m 2 ] polymer latex number Surfactant Fresh D max /D min (blue) Archivability ⁇ D min (blue) after 3d at 35°C/80% RH Light Box ⁇ D min (blue) after 3d at 30°C/85% RH Nr.
  • the silver behenate dispersion used in the preparation of the thermographic materials of INVENTION EXAMPLES 5 to 17 was prepared as described for COMPARATIVE EXAMPLES 1 to 6 and INVENTION EXAMPLES 1 to 4.
  • thermographic materials Preparation of the thermographic materials
  • the coating dispersion was prepared by adding with stirring to 24.42g of the 20% silver behenate dispersion: 15.7g of a 33.5% dispersion of polymer latex nr. 5, 22.91g of deionized water, 2g of a 9.4% aqueous solution of Surfactant 3 and 5g of ethanol.
  • the coating dispersion was prepared by adding with stirring to 24.42g of the 20% silver behenate dispersion: latex dispersion (for polymer latex number, quantity and concentration see table 8 and for surfactants present in the coating dispersion both from the latex dispersion and added during the preparation of the coating dispersion see table 9), 9.4% aqueous solution of Surfactant Nr. 3 (for quantity see table 8) and finally ethanol (for quantity see table 8).
  • Invention example number polymer latex nr. concentration of latex (%) quantity of latex dispersion [g] quantity of water [g] 9.4% solution of Surfactant Nr.
  • the silver behenate emulsion layers were overcoated with the reducing agent-containing layer used in COMPARATIVE EXAMPLES 1 to 6 and INVENTION EXAMPLES 1 to 4 to a R01 coating weight of 0.65g/m 2 .
  • thermographic materials of INVENTION EXAMPLES 5 to 17 was carried out as described above for COMPARATIVE EXAMPLES 1 to 6 and INVENTION EXAMPLES 1 to 4 and the results are summarized in table 9 below.
  • the silver behenate dispersion used in the preparation of the thermographic materials of INVENTION EXAMPLES 18 to 23 were prepared as described for COMPARATIVE EXAMPLES 1 to 6 and INVENTION EXAMPLES 1 to 4.
  • thermographic materials Preparation of the thermographic materials
  • the coating dispersion was prepared by adding with stirring to 26.35g of the 20% silver behenate dispersion: 26.25g of a 20% dispersion of polymer latex (for polymer latex nr., see table 10), 10.4g of deionized water, 2g of a 9.4% aqueous solution of surfactant 3 and 5g of ethanol.
  • the coating dispersions for INVENTION EXAMPLES 22 & 23 were prepared as for INVENTION EXAMPLES 18 to 21 except that 15.4g of deionized water was added instead of 10.4g and no ethanol (EtOH) was added.
  • the silver behenate emulsion layers were overcoated with the reducing agent-containing layer used in COMPARATIVE EXAMPLES 1 to 6 and INVENTION EXAMPLES 1 to 4 to a R01 coating weight of 0.65g/m 2 .
  • thermographic materials of INVENTION EXAMPLES 18 to 23 were carried out as described above for COMPARATIVE EXAMPLES 1 to 6 and INVENTION EXAMPLES 1 to 4 and the results are summarized in table 10 below:
  • 107g of DISPERSETM AYD W22, 282.5g of a 10% aqueous solution of Surfactant Nr 6 and 1360.5g of deionized water were well mixed and then 750g of silver behenate powder was added with stirring with a HOMOREXTM stirrer. Stirring was continued for 30 minutes after the addition of the silver behenate and then the resulting dispersion was stored for 24 hours in a refrigerator to allow the foam to dissipate. The dispersion was then stirred for 15 minutes with an ULTRA-TURRAXTM stirrer and then stirred and then passed three times through a MICROFLUIDICSTM microfluidizer at a pressure of 400 bar to obtain the final dispersion.
  • thermographic materials Preparation of the thermographic materials
  • the silver behenate emulsion was prepared by adding with stirring to 17.5g of the 32.6% silver behenate dispersion: 25.5g of a polymer latex dispersion containing 5.25g of solids (as indicated in table 11), 2g of a 9.4% aqueous solution of Surfactant 3 and 2g of ethanol.
  • the coating dispersion was prepared by adding with stirring to 17.5g of the 20% silver behenate dispersion: latex dispersion (for polymer latex number, quantity and concentration see table 11 and for the concentration of surfactant with respect to the latex added during the preparation of the coating dispersion see table 12), deionized water (for quantity see table 11), 9.4% aqueous solution of Surfactant Nr. 3 (for quantity see table 11) and finally ethanol (for quantity see table 11).
  • Invention example number polymer latex nr. concentration of latex (%) quantity of latex dispersion [g] quantity of water [g] 9.4% solution of Surfactant Nr.
  • thermographic materials of INVENTION EXAMPLES 24 to 33 was carried out as described above for COMPARATIVE EXAMPLES 1 to 6 and INVENTION EXAMPLES 1 to 4 and the results are summarized in table 12 below.
  • a 0.34mm thick polyethylene terephthalate sheet was coated to a thickness of 0.1mm with a composition which after drying and longitudinal and transverse stretching produced a 175 ⁇ m thick support coated on with the following subbing-layer composition expressed as the coating weights of the ingredients present: # copolymer of terephthalic acid/isophthalic acid/sulfoisophthalic acid/ethylene glycol (26.5/20/3.5/50): 37.0mg/m 2 # copolymer latex of ethyl acrylate/methacrylic acid (80/20): 3.0mg/m 2 # HORDAMERTM PE02: 1.0mg/m 2 # PAREZ RESINTM 707: 7.0mg/m 2
  • the tone modifier dispersion was prepared by first dissolving 8.8g of K7598 in 71.4g of deionized water by first adding the gelatin, then allowing the gelatin to swell for 30 minutes and finally heating to 50°C. 20 g of T01 was added with ULTRA-TURRAXTM stirring to this gelatin solution at 50°C, and the stirring continued for a further 5 minutes. Finally the resulting dispersion was pumped through a DYNOMILLTM (a horizontal bead mill from BACHOFEN) for 6 hours to produce the final tone modifier dispersion containing: 20% of T01 and 8.8% of gelatin.
  • DYNOMILLTM a horizontal bead mill from BACHOFEN
  • the coating dispersions for the thermographic recording materials of INVENTION EXAMPLES 33 to 44 were prepared by first dissolving 1.927g of K7598 in deionized water at 38°C (for the quantity of water see table 13), then adding with stirring to the warm K7598 solution: first 19.0g of the silver behenate dispersion, then 5.68g of the tone modifier dispersion as flakes followed by 15 minutes stirring, then the latex dispersion (for quantity, concentration and type see table 13), then 11.23g of an aqueous ethanol solution (17.6% ethanol) containing 0.92g of R02 and 0.62g of boric acid and finally 1.310g of a 3.7% by weight solution of formaldehyde to produce 60g of a dispersion containing: 7.47% of silver behenate, 0.75% of Surfactant Nr 5, 4.04% of gelatin, 2.98% of polymer latex, 1.53% of R02, 1.03% of boric acid, 1.92% of T01 and 0.08% of formaldehyde.
  • the resulting emulsions were then doctor blade-coated to a wet thickness of 60 ⁇ m at a blade setting of 100 ⁇ m onto the 175 ⁇ m thick subbed polyethylene terephthalate support and dried for 10 minutes at 50°C, producing a silver behenate coverage of about 4.0g/m 2 .
  • thermographic recording materials of INVENTION EXAMPLES 33 to 44 were carried out as described for COMPARATIVE EXAMPLES 1 to 6 and INVENTION EXAMPLES 1 to 4 except that in addition the image tone was assessed on the basis of the L*, a* and b* CIELAB-values of fresh prints.
  • Colour neutrality on the basis of CIELAB-values corresponds to a* and b* values of zero, with a negative a*-value indicating 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 b*-value indicating a bluish image-tone becoming bluer as b* becomes more negative and a positive b*-value indicating a yellowish image-tone becoming yellower as b* becomes more positive.

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • General Physics & Mathematics (AREA)
  • Heat Sensitive Colour Forming Recording (AREA)
  • Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)
EP19980202543 1997-09-17 1998-07-29 Bindemittel für thermographische Materialien Expired - Lifetime EP0903623B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP19980202543 EP0903623B1 (de) 1997-09-17 1998-07-29 Bindemittel für thermographische Materialien

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
EP97202873 1997-09-17
EP97202873 1997-09-17
EP19980202543 EP0903623B1 (de) 1997-09-17 1998-07-29 Bindemittel für thermographische Materialien

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EP0903623A1 true EP0903623A1 (de) 1999-03-24
EP0903623B1 EP0903623B1 (de) 2003-05-14

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61193142A (ja) * 1985-02-04 1986-08-27 Konishiroku Photo Ind Co Ltd 熱現像感光材料
DE3635441A1 (de) * 1985-10-18 1987-05-07 Fuji Photo Film Co Ltd Verfahren zur herstellung eines bildes
EP0226953A2 (de) * 1985-12-21 1987-07-01 Agfa-Gevaert AG Farbfotografisches Aufzeichnungsmaterial
WO1994016361A1 (en) * 1993-01-15 1994-07-21 Labelon Corporation Thermal imaging material and preparation
EP0678776A2 (de) * 1994-04-18 1995-10-25 Eastman Kodak Company Wärmeentwickelbares Aufzeichningsmaterial enthaltend eine elektrisch leitfähige Oberflächenschicht

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61193142A (ja) * 1985-02-04 1986-08-27 Konishiroku Photo Ind Co Ltd 熱現像感光材料
DE3635441A1 (de) * 1985-10-18 1987-05-07 Fuji Photo Film Co Ltd Verfahren zur herstellung eines bildes
EP0226953A2 (de) * 1985-12-21 1987-07-01 Agfa-Gevaert AG Farbfotografisches Aufzeichnungsmaterial
WO1994016361A1 (en) * 1993-01-15 1994-07-21 Labelon Corporation Thermal imaging material and preparation
EP0678776A2 (de) * 1994-04-18 1995-10-25 Eastman Kodak Company Wärmeentwickelbares Aufzeichningsmaterial enthaltend eine elektrisch leitfähige Oberflächenschicht

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Section Ch Week 8641, Derwent World Patents Index; Class A14, AN 86-267419, XP002069548 *

Also Published As

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EP0903623B1 (de) 2003-05-14
DE69814544D1 (de) 2003-06-18
DE69814544T2 (de) 2004-03-18
JPH11170709A (ja) 1999-06-29

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