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
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/0051—Tabular grain emulsions
• • 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
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/035—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein characterised by the crystal form or composition, e.g. mixed grain
• • 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
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
• • 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
  • G03C1/494—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
  • G03C3/00—Packages of films for inserting into cameras, e.g. roll-films, film-packs; Wrapping materials for light-sensitive plates, films or papers, e.g. materials characterised by the use of special dyes, printing inks, adhesives
  • G03C3/003—Individual packages for X-ray film, e.g. for dental applications
• • 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
  • G03C7/00—Multicolour photographic processes or agents therefor; Regeneration of such processing agents; Photosensitive materials for multicolour processes
  • G03C7/22—Subtractive cinematographic processes; Materials therefor; Preparing or processing such materials
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/76—Photosensitive materials characterised by the base or auxiliary layers
  • G03C1/7614—Cover layers; Backing layers; Base or auxiliary layers characterised by means for lubricating, for rendering anti-abrasive or for preventing adhesion
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/76—Photosensitive materials characterised by the base or auxiliary layers
  • G03C1/85—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
  • G03C1/95—Photosensitive materials characterised by the base or auxiliary layers rendered opaque or writable, e.g. with inert particulate additives
• • 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
  • G03C11/00—Auxiliary processes in photography
  • G03C11/16—Drying
• • 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
  • G03C1/74—Applying photosensitive compositions to the base; Drying processes therefor
  • G03C2001/7407—Specific angles in extrusion head-slide hopper
• • 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
  • G03C1/74—Applying photosensitive compositions to the base; Drying processes therefor
  • G03C2001/7411—Beads or bead coating
• • 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
  • G03C1/74—Applying photosensitive compositions to the base; Drying processes therefor
  • G03C2001/7414—Bending support to prevent coating of borders
• • 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
• • 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
  • G03C2200/00—Details
  • G03C2200/04—Adsorbent

Definitions

• the present invention relates to a thermographic and photothermographic materials and recording processes therefor.
• Thermal imaging or thermography is a recording process wherein images are generated by the use of imagewise modulated thermal energy.
• thermography three approaches are known:
• a typical heat-sensitive (thermographic) copy paper includes in the heat-sensitive layer a thermoplastic binder, e.g ethyl cellulose, a water-insoluble silver salt, e.g. silver stearate and an appropriate organic reducing agent, of which 4-methoxy-1-hydroxy-dihydronaphthalene is a representative.
• a thermoplastic binder e.g ethyl cellulose
• a water-insoluble silver salt e.g. silver stearate
• an appropriate organic reducing agent of which 4-methoxy-1-hydroxy-dihydronaphthalene is a representative.
• a heterocyclic organic toning agent such as phthalazinone is added to the composition of the heat-sensitive layer.
• Thermo-sensitive copying paper is used in "front-printing” or “back-printing” using infra-red radiation absorbed and transformed into heat in contacting infra-red light absorbing image areas of an original as illustrated in Figures 1 and 2 of US-P 3,074,809.
• Thermographic materials of type 3 can be rendered photothermographic by incorporating a photosensitive agent which after exposure to UV, visible or IR light is capable of catalyzing or participating in a thermographic process bringing about changes in colour or optical density.
• photothermographic materials are the so called “Dry Silver” photographic materials of the 3M company, which are reviewed by D.A. Morgan in “Handbook of Imaging Science”, edited by A.R. Diamond, page 43, published by Marcel Dekker in 1991.
• US-P 3,152,904 discloses an image reproduction sheet which comprises a radiation-sensitive heavy metal salt which can be reduced to free metal by a radiation wave length between an X-ray wave length and a five microns wave length and being distributed substantially uniformly laterally over said sheet, and as the image forming component an oxidation-reduction reaction combination which is substantially latent under ambient conditions and which can be initiated into reaction by said free metal to produce a visible change in colour comprising an organic silver salt containing carbon atoms and different from said heavy metal salt as an oxidizing agent and in addition an organic reducing agent containing carbon atoms, said radiation-sensitive heavy metal salt being present in an amount between about 50 and about 1000 parts per million of said oxidation-reduction reaction combination.
• WO 94/11198 discloses a recording material comprising on a support (i) a heat sensitive layer comprising a substantially light insensitive organic silver salt, (ii) a protective layer containing a matting agent dispersed in a binder and (iii) a reducing agent being present in the heat sensitive layer and/or another layer on the same side of the support carrying the heat sensitive layer.
• a heat sensitive layer comprising a substantially light insensitive organic silver salt
• a protective layer containing a matting agent dispersed in a binder and iii) a reducing agent being present in the heat sensitive layer and/or another layer on the same side of the support carrying the heat sensitive layer.
• protective layer thicknesses of at least 2 ⁇ m are necessary to avoid deformation of the material during printing and particles of matting agent sink into the protective layer during the thermal development process thereby reducing their slip properties. This can be avoided by using larger matting agent particles, but with adverse effects on the thermal contact of the thermal head with the material and on the image quality obtained.
• thermographic element comprising a support having coated thereon: (a) a thermographic emulsion layer comprising a non-photosensitive reducible source of silver, a reducing agent for silver ion, and a binder; (b) a layer adjacent to said thermographic emulsion layer comprising a binder and a polymeric fluorinated surfactant; and (c) an outermost layer which is not removed during development of said thermographic element and which is positioned on the side of said support opposite from said thermographic emulsion layer, said outermost layer consisting essentially of a plurality of optically transparent organic polymeric beads.
• the smoothness of the bead surface and shape of the bead are chosen such that the amount of reflected visible wavelengths (400nm to 700nm) of light is kept to a minimum.
• the shape of the beads is preferably spherical, oblong, ovoid, or elliptical.
• the particle diameter is preferably in a size range of 1-12 ⁇ m in average size, more preferably, 1.5 to 10um in average size; and most preferably 2-9 ⁇ m in average size, particularly with fewer than 25% of the total number of beads being outside a range of ⁇ 15% of the average size of the beads.
• the beads may be present on the surface from about 50 to 500 beads per square millimeter; more preferably 75 to 400 beads per square millimeter; and most preferably 100 to 300 beads per square millimeter.
• the increase in percent haze due to the introduction of the beads into the construction is preferably no more than 15%; more preferably no more than 8%; and most preferably no more than 6%.
• the optically transparent organic polymeric beads which alter the separation or slip characteristics of the element's surface are provided in the imaging layers in such a manner that they tend to protrude from the surface of the outermost layer.
• the thickness of the outermost backside layers are typically 0.5 to 6 ⁇ m.”
• backside compositions consisting of 0.5 to 5.8% of polymeric beads, the beads consisting of 7 ⁇ m polystyrene methacrylate and 13 ⁇ m polymethyl methacrylate beads, 83.5 to 92.7% of cellulose acetate butyrate, 1.2 to 1.3% of a polyester resin, 0.9 to 1.0% of an antihalation dye and 0.08 to 13.4% of antistat L.
• thermal development of thermographic materials with a thermal head is usually carried cut with the thermal head in contact with the coating on the thermographic emulsion side of the support.
• the fluorine-containing surfactant in the outermost layer on the thermographic emulsion side of the support in contact with the thermal head can, at the high temperatures necessary for thermal development, decompose to a small extent resulting in the production of small quantities of hydrogen fluoride, which will attack the outermost layer of the thermal head causing premature failure of the thermal head.
• rapid pulsed heating with a thermal head can be used together with image density detection to increase the image density to a predetermined standard level.
• the presence of a fluorine-containing surfactant in the protective layer of photothermographic recording materials can, therefore, also lead to premature failure of thermal heating components.
• thermographic recording material exhibiting reliable separation and transport in a thermographic printer.
• thermographic recording material exhibiting reproducibly high image quality in a thermographic printer.
• thermographic recording material not contributing to premature failure of thermal heads.
• thermographic recording material comprising a thermosensitive element on one side of a water resistant support and an outermost backside layer on the other side of the water resistant support, the thermosensitive element comprising a substantially light-insensitive organic silver salt, an organic reducing agent for the substantially light-insensitive organic silver salt in thermal working relationship therewith and a binder and the outermost backside layer comprising polymeric beads, characterized in that an outermost layer on the side of the water resistant support with the thermosensitive element does not contain a fluorine-containing polymeric surfactant and the static frictional coefficient between the outermost layer on the side of the water resistant support with the thermosensitive element and the outermost backside layer is ⁇ 0.24 and/or the outermost backside layer of the thermographic recording material has an R z determined according to DIN 4768/1 of > 1.75 ⁇ m.
• thermographic recording process comprising the steps of: (i) providing a thermographic material as referred to above; (ii) bringing the side of the water resistant support with the thermosensitive element into contact with a thermal head; (iii) image-wise heating the thermographic material by pixel-wise heating with the thermal head; and (iv) removing the thermographic recording material from the thermal head.
• a photothermographic recording material comprising a photo-addressable thermosensitive element on one side of a water resistant support and an outermost backside layer on the other side of the water resistant support, the photo-addressable thermosensitive element comprising a substantially light-insensitive organic silver salt, an organic reducing agent for the substantially light-insensitive organic silver salt in thermal working relationship therewith, photosensitive silver halide in catalytic association with the substantially light insensitive organic silver salt and a binder and the outermost backside layer comprising polymeric beads, characterized in that an outermost layer on the side of the water resistant support with the photo-addressable thermosensitive element does not contain a fluorine-containing polymeric surfactant and the static frictional coefficient between the outermost layer on the side of the water resistant support with the photo-addressable thermosensitive element and the outermost backside layer is ⁇ 0.24 and/or the outermost backside layer of the photothermographic recording material has an R z determined according to DIN 4768/1 of > 1.75
• a photothermographic recording process comprising the steps of: (i) providing a photothermographic recording material as referred to above; (ii) image-wise exposing the photo-addressable thermosensitive element with actinic radiation; (iii) bringing the image-wise exposed photothermographic recording material into proximity with a heat source; (iv) uniformly heating the image-wise exposed photothermographic recording material; and (v) removing the photothermographic recording material from said the source.
• the outermost backside layer according to the present invention comprises polymeric beads.
• Suitable beads may be produced by free radical polymerization, ionic polymerization or condensation poymerization of polymerizable monomer or monomer mixtures by, for example, suspension or emulsion polymerization and are preferably at least partially crosslinked to endow the beads with some form-stability under the high local temperatures attained during thermal development of the thermographic and photothermographic recording materials of the present invention.
• Suitable monomers are, for example, methacrylates, acrylates, styrene, butadiene, isoprene, divinylbenzene, methacrylic acid, acrylic acid, vinyl acetate, itaconic acid, halo-containing vinyl monomers and the like.
• Suitable polymeric beads can be produced as described in US-P 4,861,818 and EP-B 80 225.
• Preferred polymeric beads have a weight averaged diameter between 1 and 20 ⁇ m with diameters between 2 and 12 ⁇ m being particularly preferred.
• the outermost backside layer may further comprise a binder to promote adhesion of the polymeric beads to the support, although subbing of the support with an adhesion promoting layer may of itself be sufficient to provide the necessary adhesion.
• Suitable binders for use in the outermost backside layer may be hydrophilic or hydrophobic depending upon the choice of polymeric beads and can be present in the coating solution in dissolved form or dispersed form such as, for example, polymer latexes or polymer dispersions. Coating may be performed from aqueous or solvent media. Polymeric latexes are preferred, since these allow a hydrophobic outermost backside layer to be coated from an aqueous medium. Particularly preferred are latexes based on acrylates or methacrylates, with polymethyl methacrylate latexes being especially preferred. Suitable latexes have average particle sizes between 20 and 500nm, with average particle sizes between 30 and 200nm being particularly preferred. A cosolvent may be used during the coating process to improve the film-forming properties of the latexes e.g. N-methylpyrrolidone.
• the outermost backside layer may further comprise colloidal silica, which may be hydrophilic or hydrophobic. Hydrophilic colloidal silica is preferred with average particles sizes between 3 and 50nm. Colloidal silica can be used in an acidic or basic form with the basic form being preferred.
• the outermost backside layer may further comprise an antihalation dye, such as those disclosed in the section on antihalation dyes, to increase image sharpness upon image-wise heating of a thermographic recording material using an infra-red heat source, for example with a Nd-YAG laser or other infra-red laser, or image-wise exposure of a photothermographic recording material.
• an antihalation dye such as those disclosed in the section on antihalation dyes
• the outermost backside layer may also further comprise an antistatic species to prevent the buildup of charge due to triboelectric contact during coating, transport during finishing and packaging and in an apparatus for image-wise heating or for image-wise exposure followed by thermal development.
• an antistatic species to prevent the buildup of charge due to triboelectric contact during coating, transport during finishing and packaging and in an apparatus for image-wise heating or for image-wise exposure followed by thermal development.
• polymeric beads may be incorporated into antistatic layers.
• Suitable antistatic layers are described in EP-A's 444 326, 534 006 and 644 456, US-P's 5,364,752 and 5,472,832 and DOS 4125758.
• Particularly preferred antistatic layers are those based on polythiophene as disclosed in EP-A 628 560, US-P 5,354,613, US-P 5,372,924, US-P 5,370,981 and US-P 5,391,472.
• the outermost layer on the side of the water resistant support with the thermosensitive element has an R z determined according to DIN 4768/1 of ⁇ 1.75 ⁇ m.
• the outermost layer on the side of the water resistant support with the photo-addressable thermosensitive element has an R z determined according to DIN 4768/1 of ⁇ 1.75 ⁇ m.
• R z is defined as the average of the single peak-to-valley heights of five adjoining sampling lengths l e .
• the thickness of the outermost backside layer is preferably between 0.1 and 5 ⁇ m and particularly preferably between 0.3 and 1 ⁇ m, the outermost backside layer being preferably thinner than that of the outermost layer on the same side of the support as the thermosensitive or photo-addressable thermosensitive element.
• an antistatic layer may be provided between the support and the outermost backside layer.
• Non-outermost antistatic layers are, for example, disclosed in US-P 5,310,640, US-P 5,312,681 and US-P 5,372,924.
• thermosensitive element comprises a substantially light-insensitive organic silver salt and an organic reducing agent therefor in thermal working relationship therewith and a binder.
• the element may comprise a layer system in which the ingredients may be 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 said substantially light-insensitive organic silver salt particles so that reduction of the organic silver salt can take place.
• thermosensitive element can be rendered photo-addressable by the presence of photosensitive silver halide in catalytic association with the substantially light-insensitive organic silver salt or of a component which is capable of forming photosensitive silver halide with the substantially light-insensitive organic silver salt.
• Preferred substantially light-insensitive organic silver salts according to the present invention are silver salts of aliphatic carboxylic acids known as fatty acids, wherein the aliphatic carbon chain has preferably at least 12 C-atoms, e.g. silver laurate, silver palmitate, silver stearate, silver hydroxystearate, silver oleate and silver behenate, which silver salts are also called "silver soaps"; silver dodecyl sulphonate described in US-P 4,504,575; and silver di-(2-ethylhexyl)-sulfosuccinate described in EP-A 227 141.
• Modified aliphatic carboxylic acids with thioether group as described e.g.
• thermosensitive silver image may be produced likewise to produce a thermosensitive silver image.
• a suspension of particles containing a substantially light-insensitive organic silver salt may be obtained by using a process, comprising simultaneous metered addition of a solution or suspension of an organic compound with at least one ionizable hydrogen atom or its salt; and a solution of a silver salt to a liquid, as described in the unpublished European patent application number 95201968.5.
• Suitable organic reducing agents for the reduction of sad substantially light-insensitive organic heavy metal salts are organic compounds containing at least one active hydrogen atom linked to O, N or C, such as is the case with, mono-, bis-, tris- or tetrakis-phenols; mono- or bis-naphthols; di- or polyhydroxynaphthalenes; di- or polyhydroxybenzenes; hydroxymonoethers such as alkoxynaphthols, e.g. 4-methoxy-1-naphthol described in US-P 3,094,41; pyrazolidin-3-one type reducing agents, e.g.
• PHENIDONETM pyrazolin-5-ones; indan-1,3-dione derivatives; hydroxytetrone acids; hydroxytetronimides; 3-pyrazolines; pyrazolones; reducing saccharides; aminophenols e.g. METOLTM; p-phenylenediamines, hydroxylamine derivatives such as for example described in US-P 4,082,901; reductones e.g. ascorbic acids; hydroxamic acids; hydrazine derivatives; amidoximes; n-hydroxyureas; and the like, see also US-P 3,074,809, 3,080,254, 3,094,417 and 3,887,378.
• aromatic di- and tri-hydroxy compounds having at least two hydroxy groups in ortho- or para-position on the same aromatic nucleus, e.g. benzene nucleus, hydroquinone and substituted hydroquinones, catechol, 3-(3',4'-dihydroxyphenyl)propionic acid, pyrogallol, gallic acid and gallic acid esters are preferred.
• Particularly useful are polyhydroxy spiro-bis-indane compounds, especially these corresponding to the following general formula (I): wherein :
• polyhydroxy-spiro-bis-indane compounds described in US-P 3,440,049 as photographic tanning agent, more especially 3,3,3',3'-tetramethyl-5,6,5',6'-tetrahydroxy-1,1'-spiro-bis-indane (called indane I) and 3,3,3',3'-tetramethyl-4,6,7,4',6',7'-hexahydroxy-1,1'-spiro-bis-indane (called indane II).
• Indane is also known under the name hydrindene.
• catechol-type reducing agents by which is meant reducing agents containing at least one benzene nucleus with two hydroxy groups (-OH) in ortho-position, are preferred, e.g. 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-dihydroxybenzoic acid esters.
• catechol-type reducing agents are benzene compounds in which the benzene nucleus is substituted by no more than two hydroxy groups which are present in 3,4-position on said nucleus and have in the 1-position of said nucleus a substituent linked to said nucleus by means of a carbonyl group.
• Polyphenols such as the bisphenols used in the 3M Dry SilverTM materials, sulfonamide phenols such as used in the Kodak DacomaticTM materials, and naphthols are particularly preferred for photothermographic recording materials with photo-addressable thermosensitive elements on the basis of photosensitive silver halide/organic silver salt/reducing agent.
• the reducing agent must be present in such a way that it is able to diffuse to said substantially light-insensitive organic heavy metal salt particles so that reduction of said organic heavy metal salt can take place.
• the silver image density depends on the coverage of the above defined reducing agent(s) and organic silver salt(s) and has to be preferably such that, on heating above 80 °C, an optical density of at least 1.5 can be obtained.
• an optical density of at least 1.5 can be obtained.
• at least 0.10 moles of reducing agent per mole of organic heavy metal salt is used.
• auxiliary reducing agents are e.g. sterically hindered phenols, that on heating become reactive partners in the reduction of the substantially light-insensitive organic heavy metal salt such as silver behenate, such as described in US-P 4,001,026; or are bisphenols, e.g. of the type described in US-P 3,547,648.
• the auxiliary reducing agents may be present in the imaging layer or in a polymeric binder layer in thermal working relationship thereto.
• auxiliary reducing agents are sulfonamidophenols corresponding to the following general formula : Aryl-SO 2 -NH-Arylene-OH in which :
• auxiliary reducing agents that may be used in conjunction with the above mentioned primary reducing agents are 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 and organic reducing metal salts, e.g. stannous stearate described in US-P 3,460,946 and 3,547,648.
• 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
• organic reducing metal salts e.g. stannous stearate described in US-P 3,460,946 and 3,547,648.
• the film-forming binder for the photo-addressable thermosensitive element according to the present invention may be coatable from a solvent or aqueous dispersion medium.
• the film-forming binder for the photo-addressable thermosensitive element according to the present invention may be coatable from a solvent dispersion medium, according to the present invention, 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: e.g.
• polymers derived from ⁇ , ⁇ -ethylenically unsaturated compounds such as polyvinyl chloride, after-chlorinated polyvinyl chloride, copolymers of vinyl chloride and vinylidene chloride, copolymers of vinyl chloride and vinyl acetate, polyvinyl acetate and partially hydrolyzed polyvinyl acetate, polyvinyl acetals that are made from polyvinyl alcohol as starting material in which only a part of the repeating vinyl alcohol units may have reacted with an aldehyde, preferably polyvinyl butyral, copolymers of acrylonitrile and acrylamide, polyacrylic acid esters, polymethacrylic acid esters, polystyrene and polyethylene or mixtures thereof.
• a particularly suitable polyvinyl butyrals containing a minor amount of vinyl alcohol units are marketed under the trade name BUTVARTM B76 and BUTVARTM B79 of Monsanto USA and provides a good adhesion to paper and properly subbed polyester supports
• the film-forming binder for the photo-addressable thermosensitive element coatable from an aqueous dispersion medium may be all kinds of transparent or translucent water-dispersible or water soluble natural, modified natural or synthetic resins or mixtures of such resins, wherein the organic silver salt can be dispersed homogeneously for example proteins, such as gelatin and gelatin derivatives (e.g.
• phthaloyl gelatin cellulose derivatives, such as carboxymethylcellulose, polysaccharides, such as dextran, starch ethers etc., galactomannan, polyvinyl alcohol, polyvinylpyrrolidone, acrylamide polymers, homo-or co-polymerized acrylic or methacrylic acid, latexes of water dispersible polymers, with or without hydrophilic groups, or mixtures thereof.
• Polymers with hydrophilic functionality for forming an aqueous polymer dispersion (latex) are described e.g. in US-P 5,006,451, but serve therein for forming a barrier layer preventing unwanted diffusion of vanadium pentoxide present as an antistatic agent.
• the binder to organic heavy metal salt weight ratio is preferably in the range of 0.2 to 6, and the thickness of the recording layer is preferably in the range of 5 to 50 ⁇ m.
• 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 solid state in the recording layer at temperatures below 50°C but becomes a plasticizer for the recording layer in the heated region and/or liquid solvent for at least one of the redox-reactants, e.g. the reducing agent for the organic heavy metal salt, at a temperature above 60°C.
• redox-reactants e.g. the reducing agent for the organic heavy metal salt
• the thermosensitive element may comprise in addition at least one polycarboxylic acid and/or anhydride thereof in a molar percentage of at least 20 with respect to all said organic silver salt(s) present and in thermal working relationship therewith.
• the polycarboxylic acid may be aliphatic (saturated as well as unsaturayed aliphatic and also cycloaliphatic) or an aromatic polycarboxylic acid. These acids may be substituted e.g. with alkyl, hydroxyl, nitro or halogen. They may be used in anhydride form or partially esterified on the condition that at least two free carboxylic acids remain or are available in the heat recording step.
• saturated aliphatic dicarboxylic acids containing at least 4 carbon atoms e.g. : succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, nonane-dicarboxylic acid, decane-dicarboxylic acid, undecane-dicarboxylic acid.
• Suitable unsaturated dicarboxylic acids are : maleic acid, citraconic acid, itaconic acid and aconitic acid.
• Suitable polycarboxylic acids are citric acid and derivatives thereof, acetonedicarboxylic acid, iso-citric acid and ⁇ -ketoglutaric acid.
• Preferred aromatic polycarboxylic acids are ortho-phthalic acid and 3-nitro-phthalic acid, tetrachlorophthalic acid, mellitic acid, pyromellitic acid and trimellitic acid and the anhydrides thereof.
• the recording layer contains preferably in admixture with said organic heavy metal salts and reducing agents a so-called toning agent known from thermography or photothermography.
• Suitable toning agents are succinimide, phthalazine and the phthalimides and phthalazinones within the scope of the general formulae described in US-P 4,082,901. Further reference is made to the toning agents described in US-P 3,074,809, 3,446,648 and 3,844,797.
• Other particularly useful toning agents are the heterocyclic toner compounds of the benzoxazine dione or naphthoxazine dione type within the scope of following general formula : in which:
• a toner compound particularly suited for use in combination with polyhydroxy benzene reducing agents is 3,4-dihydro-2,4-dioxo-1,3,2H-benzoxazine described in US-P 3,951,660.
• the photosensitive silver halide used in the present invention may be employed in a range of 0.75 to 25 mol percent and, preferably, from 2 to 20 mol percent of substantially light-insensitive organic silver salt.
• the silver halide may be any photosensitive silver halide such as silver bromide, silver iodide, silver chloride, silver bromoiodide, silver chlorobromoiodide, silver chlorobromide etc.
• the silver halide may be in any form which is photosensitive including, but not limited to, cubic, orthorhombic, tabular, tetrahedral, octagonal etc. and may have epitaxial growth of crystals thereon.
• the silver halide used in the present invention may be employed without modification. However, it may be chemically sensitized with a chemical sensitizing agent such as a compound containing sulphur, selenium, tellurium etc., or a compound containing gold, platinum, palladium, iron, ruthenium, rhodium or iridium etc., a reducing agent such as a tin halide etc., or a combination thereof.
• a chemical sensitizing agent such as a compound containing sulphur, selenium, tellurium etc., or a compound containing gold, platinum, palladium, iron, ruthenium, rhodium or iridium etc.
• a reducing agent such as a tin halide etc.
• a suspension of particles containing a substantially light-insensitive silver salt of an organic carboxylic acid may be obtained by using a process, comprising simultaneous metered addition of an aqueous solution or suspension of an organic carboxylic acid or its salt; and an aqueous solution of a silver salt to an aqueous liquid, as described in the unpublished European patent application number 95201968.5.
• the silver halide may be added to the photo-addressable thermosensitive element in any fashion which places it in catalytic proximity to the substantially light-insensitive organic silver salt.
• Silver halide and the substantially light-insensitive organic silver salt which are separately formed, i.e. ex-situ or "preformed", in a binder can be mixed prior to use to prepare a coating solution, but it is also effective to blend both of them for a long period of time.
• it is effective to use a process which comprises adding a halogen-containing compound to the organic silver salt to partially convert the substantially light-insensitive organic silver salt to silver halide as disclosed in US-P 3,457,075.
• a particularly preferred mode of preparing the emulsion of organic silver salt and photosensitive silver halide for coating of the photo-addressable thermosensitive element from solvent media, according to the present invention is that disclosed in US-P 3,839,049, but other methods such as those described in Research Disclosure, June 1978, item 17029 and US-P 3,700,458 may also be used for producing the emulsion.
• the photo-addressable thermosensitive element of the photothermographic recording material may contain a spectral sensitizer, optionally together with a supersensitizer, for the silver halide.
• the silver halide may be spectrally sensitized with various known dyes including cyanine, merocyanine, styryl, hemicyanine, oxonol, hemioxonol and xanthene dyes optionally, particularly in the case of sensitization to infrared radiation, in the presence of a so-called supersensitizer.
• Useful cyanine dyes include those having a basic nucleus, such as a thiazoline nucleus, an oxazoline nucleus, a pyrroline nucleus, a pyridine nucleus, an oxazole nucleus, a thiazole nucleus, a selenazole nucleus and an imidazole nucleus.
• a basic nucleus such as a thiazoline nucleus, an oxazoline nucleus, a pyrroline nucleus, a pyridine nucleus, an oxazole nucleus, a thiazole nucleus, a selenazole nucleus and an imidazole nucleus.
• Useful merocyanine dyes which are preferred include those having not only the above described basic nuclei but also acid nuclei, such as a thiohydantoin nucleus, a rhodanine nucleus, an oxazolidinedione nucleus, a thiazolidinedione nucleus, a barbituric acid nucleus, a thiazolinone nucleus, a malononitrile nucleus and a pyrazolone nucleus.
• acid nuclei such as a thiohydantoin nucleus, a rhodanine nucleus, an oxazolidinedione nucleus, a thiazolidinedione nucleus, a barbituric acid nucleus, a thiazolinone nucleus, a malononitrile nucleus and a pyrazolone nucleus.
• imino groups or carboxyl groups are particularly effective.
• Suitable sensitizers of silver halide to infra-red radiation include those disclosed in the EP-A's 465 078, 559 101, 616 014 and 635 756, the JN's 03-080251, 03-163440, 05-019432, 05-072662 and 06-003763 and the US-P's 4,515,888, 4,639,414, 4,713,316, 5,258,282 and 5,441,866.
• Suitable supersensitizers for use with infra-red spectral sensitizers are disclosed in EP-A's 559 228 and 587 338 and in the US-P's 3,877,943 and 4,873,184.
• the photothermographic recording material of the present invention may contain anti-halation or acutance dyes which absorb light which has passed through the photosensitive layer, thereby preventing its reflection.
• Such dyes may be incorporated into the photo-addressable thermosensitive element or in any other layer comprising the photothermographic recording material of the present invention.
• the anti-halation dye may also be bleached either thermally during the thermal development process, as disclosed in the US-P's 4,033,948, 4,088,497, 4,153,463, 4,196,002, 4,201,590, 4,271,263, 4,283,487, 4,308,379, 4,316,984, 4,336,323, 4,373,020, 4,548,896, 4,594,312, 4,977,070, 5,258,274, 5,314,795 and 5,312,721, or photo-bleached after the thermal development process, as disclosed in the US-P,s 3,984,248, 3,988,154, 3,988,156, 4,111,699 and 4,359,524.
• anti-halation layer may be contained in a layer which can be removed subsequent to the exposure process, as disclosed in US-P 4,477,562 and EP-A 491 457.
• Suitable anti-halation dyes for use with infra-red light are described in the EP-A's 377 961 and 652 473, the EP-B's 101 646 and 102 781 and the US-P's 4,581,325 and 5,380,635.
• the (photo-addressable) thermosensitive element may contain other additives such as free fatty acids, surface-active 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. BAYSILONETM ⁇ l A (from BAYER AG, GERMANY), ultraviolet light absorbing compounds, white light reflecting and/or ultraviolet radiation reflecting pigments, silica, colloidal silica, fine polymeric particles [e.g. of poly(methylmethacrylate)] and/or optical brightening agents.
• surface-active 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. BAYSILONETM ⁇ l A (from BAYER AG, GERMANY)
• ultraviolet light absorbing compounds e
• the support for the (photo)thermographic recording material according to the present invention may be transparent, translucent or opaque, e.g. having a white light reflecting aspect 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, corona and flame treated polypropylene, polystyrene, polymethacrylic acid ester, polycarbonate or polyester, e.g. polyethylene terephthalate or polyethylene naphthalate as disclosed in GB 1,293,676, GB 1,441,304 and GB 1,454,956.
• a paper base substrate is present which may contain white reflecting pigments, optionally also applied in an interlayer between the recording material and the paper base substrate.
• the support may be in sheet, ribbon or web form and subbed or pretreated, if need be to improve the adherence to the thereon coated thermosensitive element and antistatic outermost backing layer.
• Suitable subbing layers for improving the adherence of the thermosensitive element and the antistatic layer outermost backing layer of the present invention for polyethylene terephthalate supports are described e.g. in GB-P 1,234,755, US-P 3,397,988; 3,649,336; 4,123,278 and US-P 4,478,907 which relates to subbing layers applied from aqueous dispersion of sulfonated copolyesters, and further the subbing layers described in Research Disclosure published in Product Licensing Index, July 1967, p. 6.
• Suitable pretreatments of hydrophobic resin supports are, for example, treatment with a corona discharge and/or attack by solvent(s), thereby providing a micro-roughening.
• the support may be made of an opacified resin composition, e.g. polyethylene terephthalate opacified by means of pigments and/or micro-voids and/or coated with an opaque pigment-binder layer, and may be called synthetic paper, or paperlike film; information about such supports can be found in EP's 194 106 and 234 563 and US-P's 3,944,699, 4,187,113, 4,780,402 and 5,059,579. Should a transparent base be used, the base may be colourless or coloured, e.g. having a blue colour.
• thermosensitive element Outermost layer on same side of support as thermosensitive element
• the outermost layer of the (photo)thermographic recording material may in different embodiments of the present invention be the outermost layer of the (photo-addressable) thermosensitive element or a protective layer applied to the (photo-addressable) thermosensitive element.
• the (photo-addressable) thermosensitive element may be provided with an outermost layer comprising at least one lubricant to improve the slipping properties of the (photo) thermographic recording material.
• at least one solid lubricant having a melting point below 150°C and at least one liquid lubricant in a binder is used, wherein at least one of the lubricants is a phosphoric acid derivative.
• Suitable solid lubricants have a melting point below 150°C.
• solid lubricants having a melting point below 110°C, with solid lubricants with a molecular weight below 1000 being particularly preferred.
• solid lubricants are defined as those lubricants being solid at room temperature.
• Solid lubricants which can be used according to the present invention are polyolefin waxes e.g. polypropylene waxes, ester waxes e.g. fatty acid esters, polyolefin-polyether block copolymers, amide waxes e.g. fatty acid amides, polyglycols e.g. polyethylene glycol, fatty acids, fatty alcohols, natural waxes and solid phosphoric acid derivatives.
• polyolefin waxes e.g. polypropylene waxes
• ester waxes e.g. fatty acid esters
• polyolefin-polyether block copolymers amide waxes e.g. fatty acid amides
• polyglycols e.g. polyethylene glycol
• fatty acids fatty alcohols
• natural waxes and solid phosphoric acid derivatives.
• Preferred solid lubricants are fatty acid esters, polyolefin-polyether block copolymers and fatty acid amides.
• Preferred fatty acid esters are glycerine monostearate, glycerine monopalmitate and mixtures of glycerine monostearate and glycerine monopalmitate.
• Preferred fatty acid amides are selected from the group consisting of ethylenebisstearamide, stearamide, oleamide, myristamide and erucamide.
• thermosensitive binder for outermost layer on same side of support as thermosensitive element
• the outermost layer of the (photo)thermographic recording material may comprise a hydrophilic binder.
• Suitable hydrophilic binders for the outermost layer are, for example, gelatin, polyvinylalcohol, cellulose derivatives or other polysaccharides, hydroxyethylcellulose, hydroxypropylcellulose etc., with hardenable binders being preferred and polyvinylalcohol being particularly preferred.
• the outermost layer of the (photo)thermographic recording material may be crosslinked.
• Crosslinking can be achieved by using crosslinking agents such as described in WO 95/12495 for protective layers, e.g. tetraalkoxysilanes, polyisocyanates, zirconates, titanates, melamine resins etc., with tetraalkoxysilanes such as tetramethylorthosilicate and tetraethylorthosilicate being preferred.
• the outermost layer comes into contact with a thermal head during thermal processing, the outermost layer is preferably crosslinked.
• the outermost layer of the (photo)thermographic recording material according to the present invention may comprise a matting agent.
• Suitable matting agents are described in WO 94/11198 and include e.g. talc particles and optionally protrude from the outermost layer.
• the outermost layer of the (photo)thermographic recording material on the same side of the support as the (photo-addressable) thermosensitive layer, according to the present invention, may be a protective layer applied to the (photo-addressable) thermosensitive element to avoid local deformation of the (photo-addressable) thermosensitive element and to improve resistance against abrasion.
• the protective layer preferably comprises a binder, which may be hydrophobic (solvent soluble) of hydrophilic (water soluble).
• a binder which may be hydrophobic (solvent soluble) of hydrophilic (water soluble).
• hydrophobic binders polycarbonates as described in EP-A 614 769 are particularly preferred.
• hydrophilic binders are preferred for the protective layer, as coating can be performed from an aqueous composition and mixing of the hydrophilic protective layer with the immediate underlayer can be avoided by using a hydrophobic binder in the immediate underlayer.
• a protective layer according to the present invention may comprise in addition at least one solid lubricant having a melting point below 150°C and at least one liquid lubricant in a binder, wherein at least one of the lubricants is a phosphoric acid derivative, further dissolved lubricating material and/or particulate material, e.g. talc particles, optionally protruding from the outermost layer.
• suitable lubricating materials are surface active agents, liquid lubricants, solid lubricants which do not melt during thermal development of the recording material, solid lubricants which melt (thermomeltable) during thermal development of the recording material or mixtures thereof.
• the lubricant may be applied with or without a polymeric binder.
• the surface active agents may be any agents known in the art such as carboxylates, sulfonates, aliphatic amine salts, aliphatic quaternary ammonium salts, polyoxyethylene alkyl ethers and polyethylene glycol fatty acid esters.
• Examples of liquid lubricants include silicone oils, synthetic oils, saturated hydrocarbons and glycols.
• Examples of solid lubricants include various higher alcohols such as stearyl alcohol and fatty acids.
• Such protective layers may also comprise particulate material, e.g. talc particles, optionally protruding from the protective outermost layer as described in WO 94/11198.
• Other additives can also be incorporated in the protective layer e.g. colloidal particles such as colloidal silica.
• any layer of the (photo)thermographic recording materials of the present invention may proceed by any thin-film coating technique known in the art.
• slide hopper coating is used advantageously, but other coating techniques such as dip coating and air knife coating may also be used. Details about such coating techniques can be found in "Modern Coating and Drying Technology" by Edward D. Cohen and Edgar B. Gutoff, published by VCH Publishers, Inc. 220 East 23rd Street, Suite 909 New York, NY 10010.
• thermographic recording materials Processing configurations for thermographic recording materials
• 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 into heat via Joule effect.
• the electric pulses thus converted into thermal signals manifest themselves as heat transferred to the surface of the thermal paper wherein the chemical reaction resulting in colour development takes place.
• 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 50ms or less, the pressure contact of the thermal printhead with the recording material being e.g. 100-500g/cm 2 to ensure a good transfer of heat.
• the imagewise 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.
• the direct thermal image-wise heating of the recording material proceeds by Joule effect heating in that selectively energized electrical resistors of a thermal head array are used in contact or close proximity with the recording layer.
• Suitable thermal printing heads are e.g. a Fujitsu Thermal Head (FTP-040 MCS001), a TDK Thermal Head F415 HH7-1089 and a Rohm Thermal Head KE 2008-F3.
• the image signals for modulating the 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
• Activation of the heating elements can be power-modulated or pulse-length modulated at constant power.
• Photothermographic recording materials may be exposed with radiation of wavelength between an X-ray wavelength and a 5 microns wavelength with the image either being obtained by pixel-wise exposure with a finely focussed light source, such as a CRT light source; a UV, visible or IR wavelength laser, such as a He/Ne-laser or an IR-laser diode, e.g. emitting at 780nm, 830nm or 850nm; or a light emitting diode, for example one emitting at 659nm; or by direct exposure to the object itself or an image therefrom with appropriate illumination e.g. with UV, visible or IR light.
• a finely focussed light source such as a CRT light source
• a UV, visible or IR wavelength laser such as a He/Ne-laser or an IR-laser diode, e.g. emitting at 780nm, 830nm or 850nm
• a light emitting diode for
• any sort of heat source can be used that enables the recording materials to be uniformly heated to the development temperature in a time acceptable for the application concerned e.g. contact heating with for example a heated roller or a thermal head, radiative heating, microwave heating etc.
• thermographic and photothermographic recording materials of the present invention can be used for both the production of transparencies and reflection type prints.
• the support will be transparent or opaque, e.g. having a white light reflecting aspect.
• a paper base substrate is present which may contain white reflecting pigments, optionally also applied in an interlayer between the recording material and the paper base substrate. Should a transparent base be used, the base may be colourless or coloured, e.g. has a blue colour.
• the static and dynamic frictional coefficients between two materials was determined by fastening a 35 x 274 mm strip with the first material uppermost, placing a 35 x 274 mm strip with the second material in contact with the uppermost layer of the first strip, attaching the end of the second strip to a calibrated strain gauge either directly as in the case of dynamic measurements or via a spring (spring constant 0.2N/m) as in the case of static measurements, placing a 117g hard rubber roller on the second strip, setting the strain gauge in motion at a constant speed of 15cm/minute in a horizontal direction over a displacement of 13cm and recording the voltage output from the strain gauge.
• the values given in the invention and comparative examples are the average values of four measurements with different strips carried out at 21°C and 50% relative humidity, the strips being conditioned in this atmosphere for at least 4 hours before the measurements are carried out.
• thermosensitive element thermosensitive element
• thermosensitive element
• a 0.34mm transparent blue polyethylene terephthalate sheet was coated on both sides to a thickness of 0.1mm with a subbing layer composition which after drying and longitudinal and transverse stretching produced a 175 ⁇ m thick support coated on both sides with the following subbing-layer composition expressed as the coating weights of the ingredients present: # terpolymer latex of vinylidene chloride/methyl acrylate/itaconic acid (88/10/2): 0.16g/m 2 # colloidal silica (KieselsolTM 100F from BAYER) : 0.04g/m 2 # alkyl sulfonate surfactant (MersolatTM H from BAYER) : 0.6mg/m 2 # aryl sulfonate surfactant (UltravonTM W from CIBA-GEIGY): 4mg/m 2
• the 175 ⁇ m thick longitudinally stretched polyethylene terephthalate support was then coated on one side with different backside layer compositions which after drying at 130°C produced the following layer compositions, expressed as the coating weights of the ingredients present: # polysaccharide (KelzanTM S from MERCK & CO, KELCO DIV.): 10mg/m 2 # polyethylenedioxythiophene: 5mg/m 2 # polystyrene sulfonic acid: 10mg/m 2 # aryl sulfonate surfactant (UltravonTM W from CIBA-GEIGY): 21mg/m 2 # polyethylene wax (PerapretTM PE40 from BASF): 10mg/m 2 # polymethylmethacrylate latex: 200mg/m 2 together with the polymer beads and colloidal silica (KieselsolTM 100F from BAYER) as specified with the results concerning the transport properties of the complete materials in table 1.
• # polysaccharide KelzanTM
• thermosensitive element with the following composition: # silver behenate: 4.90g/m 2 # polyvinyl butyral (ButvarTM B79 from MONSANTO): 19.62g/m 2 # silicone oil (BaysilonTM MA from BAYER) : 0.045g/m 2 # benzo[e][1,3]oxazine-2,4-dione: 0.268g/m 2 # 7-(ethylcarbonato)benzo[e][1,3]oxazine-2,4-dione: 0.138g/m 2 # ethyl 3,4-dihydroxybenzoate: 1.003g/m 2 # adipic acid: 0.352g/m 2 # benzotriazo
• thermosensitive element was then coated with an aqueous composition.
• the pH of the coating composition was adjusted to a pH of 4 by adding 1N nitric acid.
• Those lubricants which were insoluble in water, were dispersed in a ball mill with, if necessary, the aid of a dispersion agent.
• composition was coated to a wet layer thickness of 85 ⁇ m and then dried at 40°C for 15 minutes and hardened at 45°C and a relative humidity of 70% for 7 days to produce a layer with the following composition expressed as the coating weight of the ingredients present: # polyvinylalcohol (MowiviolTM WX 48 20, Wacker Chemie): 4.9g/m 2 # dispersion agent (UltravonTM W from Ciba Geigy)*: 0.075g/m 2 # colloidal silica (LevasilTM VP AC 4055 from Bayer AG, a 15% aqueous dispersion of colloidal silica) : 1.05g/m 2 # mono[isotridecyl polyglycolether (3 EO)] phosphate (ServoxylTM VPDZ 3/100 from Servo Delden): 0.075g/m 2 # mixture of monolauryl and dilauryl phosphates (Servoxyl VPAZ 100 from Servo Delden): 0.075g/m
• thermographic recording materials of invention examples 1 to 4 were printed using a DRYSTARTM 2000 printer (from AGFA-GEVAERT) at an average printing power of 63mW/dot.
• the printed images obtained all exhibited maximum densities,measured through a visual filter with a MacbethTM TR924 densitometer, between 3.00 and 3.40 and minimum densities below 0.10.
• the uniformity of the printed images was excellent at all optical density levels between the maximum and minimum densities i.e. no pinholes were present.
• the surface roughness of the protective and outermost backside layers were evaluated with a PERTHOMETERTM apparatus from PERTHEN AG and the R z values determined according to DIN 4768/1, where R z is the average of the single peak-to-valley heights of five adjoining sampling lengths l e .
• the R z -values found for the protective and outermost backside layers of the thermographic recording materials of invention example 2 and comparative example 2 are given in table 2.
• thermographic recording materials of invention examples 1 to 4 and comparative examples 1 and 2 The frictional coefficient between the outermost backside layer of the thermographic recording materials of invention examples 1 to 4 and comparative examples 1 and 2 and the protective layers thereof as described above with the outermost layer on the same side of the support as the thermosensitive element of the first strip mounted uppermost on the platform and the outermost backside layer of the second strip in contact therewith.
• the results for the thermographic materials of invention examples 1 to 4 and comparative examples 1 and 2 are given in table 2.
• the protective layer was hardened at 45°C and 70% relative humidity for 7 days.
• the materials of comparative examples 1 and 2 and invention examples 1 to 4 two packs of 50 sheets each were produced and one of them was subjected to 35°C and 80% relative humidity for an additional 7 days and the other to 45°C and 70% relative humidity for an additional 7 days.
• thermographic recording materials of invention examples 1 to 4 all exhibited a ⁇ static value ⁇ 0.24 and at least a satisfactory transport performance, whereas the thermographic recording materials of comparative examples 1 and 2 exhibited ⁇ static values > 0.24 and a very poor transport performance.
• PET polyethyleneterephthalate
• subbing layer consisting of a terpolymer latex of vinylidene chloride-methyl acrylate-itaconic acid (88/10/2) in admixture with colloidal silica (surface area 100m 2 /g).
• colloidal silica surface area 100m 2 /g.
• An silver halide emulsion consisting of 3.11% by weight of silver halide particles consisting of 97mol% silver bromide and 3mol% silver iodide with an weight average particle size of 50nm, 0.47% by weight of GEL as dispersing agent in deionized water was prepared using conventional silver halide preparation techniques such as described, for example, in T.H. James, "The Theory of the Photographic Process", Fourth Edition, Macmillan Publishing Co. Inc., New York (1977), Chapter 3, pages 88-104.
• the silver behenate/silver halide emulsion was prepared by adding a solution of 6.8kg of behenic acid in 67L of 2-propanol at 65°C to a 400L vessel heated to maintain the temperature of the contents at 65°C, converting 96% of the behenic acid to sodium behenate by adding with stirring 76.8L of 0.25M sodium hydroxide in deionized water, then adding with stirring 10.5kg of the above-described silver halide emulsion at 40°C and finally adding with stirring 48L of a 0.4M solution of silver nitrate in deionized water. Upon completion of the addition of silver nitrate the contents of the vessel were allowed to cool and the precipitate filtered off, washed, slurried with water, filtered again and finally dried at 40°C for 72 hours.
• An emulsion layer coating composition for the photothermographic recording materials of invention examples 5 and 6 was prepared by adding the following solutions or liquids to the above-mentioned silver behenate/silver halide emulsion in the following sequence with stirring: 0.8g of a 11.5% solution of PHP in methanol followed by a 2 hours stirring, 1g of 2-butanone, 0.2g of a 11% solution of calcium bromide in methanol and 1g of 2-butanone followed by 30 minutes stirring, 0.6g of CBBA, 1.33g of a 0.2% solution of SENSI in 99:1 methanol:triethylamine and 0.04g of MBI followed by 15 minutes stirring, 2.78g of LOWINOX and finally 0.5g of TMPS followed by 15 minutes stirring.
• a protective layer coating composition for the photothermographic recording materials of invention examples 5 and 6 were prepared by dissolving 4.08g of CAB and 0.16g of PMMA in 56.06g of 2-butanone and 5.2g methanol and adding ingredients with stirring in the following sequence: 0.5g of phthalazine, 0.2g of 4-methylphthalic acid, 0.1g of tetrachlorophthalic acid, 0.2g of tetrachlorophthalic acid anhydride and optionally 50mg of TEGOGLIDETM 410 (from GOLDSCHMIDT).
• the photothermographic recording materials of invention examples 5 and 6 were exposed to a 849nm single mode diode laser beam from SPECTRA DIODE LABS with a nominal power of 100mW of which 50mW actually reaches the recording material focussed to give a spot diameter (1/e 2 ) of 28 ⁇ m, scanned at speed of 50m/s with a pitch of 14 ⁇ m through a wedge filter with optical density varying between 0 and 3.0 in optical density steps of 0.15.
• the surface roughness of the protective and outermost backside layers were evaluated with a PERTHOMETERTM apparatus from PERTHEN AG and the R z values determined according to DIN 4768/1, where R z is the average of the single peak-to-valley heights of five adjoining sampling lengths l e .
• the R z -values found for the protective and outermost backside layers of the photothermographic recording materials of invention examples 5 and 6 are given in table 6.
• thermographic recording materials of invention examples 1 to 4 and comparative examples 1 and 2 The transport performance was evaluated qualitatively as described for the thermographic recording materials of invention examples 1 to 4 and comparative examples 1 and 2, the results also being given in table 6.
• Table 6 Invention example number Protective layer Outermost backside layer Frictional coefficient between protective and outer backside layers Transport performance number R z [ ⁇ m] number R z [ ⁇ m] ⁇ static ⁇ dynamic 5 P01 0.22 B02 0.32 0.14 0.13 1-2 6 P01 0.23 B01 2.07 0.10 0.09 0
• the photothermographic recording materials of invention examples 5 and 6 exhibited a ⁇ static value ⁇ 0.24 (invention example 5) or both a ⁇ static value ⁇ 0.24 and an R z for the backside layer > 1.75 ⁇ m (invention example 6) together with R z for the protective layer ⁇ 1.75 ⁇ m. A satisfactory transport performance was also observed for the two materials.

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• 1997
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