EP0831364B1 - Verfahren zur Herstellung eines Bildes nach dem Wärmeverfahren - Google Patents

Verfahren zur Herstellung eines Bildes nach dem Wärmeverfahren Download PDF

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Publication number
EP0831364B1
EP0831364B1 EP19960202650 EP96202650A EP0831364B1 EP 0831364 B1 EP0831364 B1 EP 0831364B1 EP 19960202650 EP19960202650 EP 19960202650 EP 96202650 A EP96202650 A EP 96202650A EP 0831364 B1 EP0831364 B1 EP 0831364B1
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EP
European Patent Office
Prior art keywords
layer
heat
laser
binder
reducing agent
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French (fr)
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EP0831364A1 (de
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Eddie Daems
Rita Torfs
Luc Leenders
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Agfa Gevaert NV
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Agfa Gevaert NV
Agfa Gevaert AG
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Priority to DE69631131T priority Critical patent/DE69631131D1/de
Priority to EP19960202650 priority patent/EP0831364B1/de
Priority to US08/917,287 priority patent/US5814430A/en
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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 method for obtaining a heat mode image with improved storage properties, and to a corresponding thermal imaging medium.
  • Conventional photographic materials based on silver halide are used for a large variety of applications. For instance, in the prepress sector of graphic arts rather sensitive camera materials are used for obtaining screened images. Scan films are used for producing colour separations from multicolour originals.
  • Phototype setting materials record the information fed to phototype- and image setters. Relative insensitive photographic materials serve as duplicating materials usually in a contact exposure process. Other fields include materials for medical recording, duplicating and hard copy, X-ray materials for non-destructive testing, black-and-white and colour materials for amateur- and professional still photography and materials for cinematographic recording and printing.
  • Silver halide materials have the advantage of high potential intrinsic sensitivity and excellent image quality. On the other hand they show the drawback of requiring several wet processing steps employing chemical ingredients which are suspect from an ecological point of view.
  • a dry imaging system known since quite a while is 3M's dry silver technology. It is a catalytic process which couples the light-capturing capability of silver halide to the image-forming capability of organic silver salts.
  • silver halide preferably silver bromide
  • silver halide is formed in situ by reacting silver behenate with bromide ions.
  • the result of this process is the formation of very fine grains of silver bromide, less than 500 angstroms in diameter and positioned in catalytic proximity to the silver behenate.
  • Exposure to light causes photolytic reduction at the silver bromide crystal (latent image formation) and provides a silver nucleus in position to permit electron transfer that catalyzes the reduction of the organic silver salt to silver metal at an elevated temperature thus producing a visual density.
  • a disadvantage of this technology is that in the non-exposed areas silver halide remains which forms print-out silver on aging thereby increasing the minimal density eventually to an unacceptable level for some purposes. Details on the dry silver technology can be found in US-P's 3,457,075, 3,839,049, 4,260,677 and J. Phot. Sci. , Vol. 41 (1993), p. 108.
  • Non-conventional materials as alternative for silver halide is based on photopolymerisation.
  • photopolymerizable compositions for the production of images by information-wise exposure thereof to actinic radiation is known since quite a while. All these methods are based on the principle of introducing a differentiation in properties between the exposed and non-exposed parts of the photopolymerizable composition e.g. a difference in solubility, adhesion, conductivity, refractive index, tackiness, permeability, diffusibility of incorporated substances e.g. dyes etc..
  • the thus produced differences may be subsequently employed in a dry treatment step to produce a visible image and/or master for printing e.g. a lithographic or electrostatic printing master.
  • thermographic materials As a further alternative for silver halide chemistry dry imaging elements are known that can be image-wise exposed using an image-wise distribution of heat. When this heat pattern is applied directly by means of a thermal head such elements are called thermographic materials. When'the heat pattern is applied by the transformation of intense laser light into heat these elements are called heat mode materials or thermal imaging media. They offer the additional advantage compared to most photo mode systems that they do not need to be handled in a dark room nor is any other protection from ambient light needed.
  • Heat mode recording materials based on change of adhesion, are disclosed in e.g. US-P 4,123,309, US-P 4,123,578, US-P 4,157,412, US-P 4,547,456 and PCT publ. Nos. WO 88/04237, WO 93/03928, and WO 95/00342.
  • a thermal imaging medium comprises a transparent support and an imaging layer containing carbon black, optionally additional layers and a stripping sheet.
  • heat mode recording materials information is recorded by creating differences in reflection and/or in transmission optical density on the recording layer.
  • the recording layer has high optical density and absorbs radiation beams which impinge thereon.
  • the conversion of radiation into heat brings about a local temperature rise, causing a thermal change such as evaporation or ablation to take place in the recording layer.
  • the irradiated parts of the recording layer are totally or partially removed, and a difference in optical density is formed between the irradiated parts and the unirradiated parts (cf. US Pat. Nos. 4,216,501, 4,233,626, 4,188,214 and 4,291,119 and British Pat. No. 2,026,346).
  • the recording layer of such heat mode recording materials is usually made of metals, dyes, or polymers.
  • thermographic and heat mode elements density is generated by image-wise chemical reduction of organic metal salts, preferably silver salts such as silver behenate, without the presence of catalytic amounts of exposed silver halide such it is the case in the dry silver system.
  • organic metal salts preferably silver salts such as silver behenate
  • catalytic amounts of exposed silver halide such it is the case in the dry silver system.
  • the separated acceptor element is subjected to an overall heat treatment.
  • a disadvantage of the cited invention lies in the fact that the obtainable density and the sharpness of the obtained image are mediocre.
  • An optional mono-sheet version of the described invention on the other hand would show problems with a rather limited shelf life.
  • the present invention extends the teachings on the formation of heat mode images based on the reduction of organic metal salts, and constitutes an improvement to the teachings of EP 0 674 217, cited above.
  • the objects of the present invention are realised by providing a method, and a corresponding material, for obtaining a heat mode image comprising the following steps :
  • the objects of the present invention are realized by providing a method for obtaining a heat mode image comprising the following steps :
  • the reducible organic metal salt is silver behenate
  • the barrier layer comprises nitrocellulose optionally hardened
  • the laser exposure is performed by an infra-red laser.
  • a transparent organic resin support can be chosen from, e.g., cellulose nitrate film, cellulose acetate film, polyvinyl acetal film, polystyrene film, polyethylene terephthalate film, polycarbonate film, polyvinylchloride film or poly- ⁇ -olefin films such as polyethylene or polypropylene film.
  • the thickness of such organic resin film is preferably comprised between 0.05 and 0.35 mm.
  • These organic resin supports are preferably coated with a subbing layer.
  • the most preferred transparent support is a polyethylene terephthalate support.
  • An example of a suitable subbing layer is a layer containing a polymer containing covalently bound chlorine. Suitable chlorine containing polymers are e.g.
  • a preferred chlorine containing polymer is co(vinylidenechloride-methylacrylate-itaconic acid ; 88 % / 10 % / 2 %).
  • a most suitable subbing layer contains the latter polymer and a colloidal silica such as KIESELSOL 100F (Bayer AG).
  • An alternative option for the transparent support is a thin glass support.
  • Suitable reducing agents for use in the layers (2) or (6') include pyrogallol, 4-azeloyl-bis-pyrogallol, 4-stearyl pyrogallol, galloacetophenone, di-tertiary-butyl pyrogallol, gallic acid anilide, methyl gallate, sodium gallate, ethyl gallate, normal- and iso-propyl gallate, butyl gallate, dodecyl gallate, gallic acid, ammonium gallate, ethyl protocatechuate, cetyl protocatechuate, 1-hydroxy-2-naphthoic acid, 2-hydroxy-3-naphthoic acid, phloroglucinol, catechol, 2,3-naphthalene diol, 4-lauroyl catechol, protocatechualdehyde, 4-methyl esculetin, 3,4-dihydroxy benzoic acid and its esters, 2,3-dihydroxy benzoic acid and its esters
  • Further useful reducing agents comprise aminocycloalkenone compounds, esters of amino reductones, N-hydroxyurea derivatives, hydrazones of aldehyde and ketones, phosphoramidophenols, phosphor amidoanilines, (2,5-dihydroxyphenyl)sulphone, tetrahydroquinoxalines, 1,2,3,4-tetrahydroquinoxaline, amidoximes, azines, hydroxamic acids, sulphonamidophenols, 2-phenylindane-1,3-dione, 1-4-dihydropyridines, such as 2,6-dimethoxy-3,5-dicarbethoxy-1,4-dihydropyridine.
  • Still other useful reducing agents include resorcins, m-aminophenols, ⁇ -and ⁇ -naphtols, alkylphenols and alkoxynaphtols.
  • a further class of reducing agents is constituted by hydrazine compounds.
  • Especially preferred hydrazine compounds include p-tolylhydrazine hydrochloride, N,N-phenylformylhydrazide, acetohydrazide, benzoylhydrazide, p-toluenesulphonylhydrazide, N,N'-diacetylhydrazine, ⁇ -acetyl-phenylhydrazine, etc.
  • esters of gallic acid especially ethyl gallate and dodecyl gallate.
  • the barrier layer (3) or (4') is destructible by the heat converted from laser radiation in the sense that its binder is ablatable or decomposable.
  • decomposable binder as used here means a binder that thermally decomposes thereby rapidly giving rise to significant amounts of gases and volatile fragments at temperatures achieved during laser imaging.
  • the polymeric binders used in the barrier layer (3) are selected from a cellulose derivative, a polycarbonate, a polystyrene and a polyurethane.
  • the polymeric binders that can be used in the barrier layer (4') include cellulosic derivatives, e.g.
  • a most preferred polymeric binder is cellulose nitrate (commonly termed nitrocellulose).
  • nitrocellulose can be unhardened, but, especially in the mono-sheet version, it is preferred to use a barrier layer containing a hardened nitrocellulose.
  • the hardening is performed by cross-linking the free hydroxyl groups of the nitrocellulose by chemical reaction with e.g. isocyanates, phenols, dialdehydes, epoxy compounds, and melamines.
  • the cross-linking is performed by an overall heat treatment.
  • a preferred way of obtaining a hardened nitrocellulose is combining it in the coating solution of the barrier layer with hexamethylenediisocyanate (such as DESMODUR N75 from Bayer AG) and zinc octanoate, which acts as a catalyst, and subjecting the coated barrier layer to heat curing.
  • hexamethylenediisocyanate such as DESMODUR N75 from Bayer AG
  • zinc octanoate which acts as a catalyst
  • the radiation to heat converting dye that transforms the information-wise modulated laser radiation into an information-wise modulated pattern of heat.
  • the laser is an infra-red laser like a diode laser or a NdYAG laser and the radiation to heat converting substance is an infra-red absorbing dye.
  • Infra-red absorbing dyes absorbing above 700 nm, are known since a long time and belong to several different chemical classes, e.g. indoaniline dyes, oxonol dyes, porphine derivatives, anthraquinone dyes, merostyryl dyes, pyrylium compounds and sqarylium derivatives.
  • a suitable infra-red dye can be chosen from the numerous disclosures and patent applications in the field, e.g., from US-Patent No's 4,886,733, 5,075,205, 5,077,186, 5,153,112, 5,244,771, from Japanese unexamined patent publications (Kokai) No.'s 01-253734, 01-253735, 01-253736, 01-293343, 01-234844, 02-3037, 02-4244, 02-127638, 01-227148, 02-165133, 02-110451, 02-234157, 02-223944, 02-108040, 02-259753, 02-187751, 02-68544, 02-167538, 02-201351, 02-201352, 03-23441, 03-10240, 03-10239, 03-13937, 03-96942, 03-217837, 03-135553, 03-235940, and from the European published patent application No.'s 0 483 740, 0 502 508, 0 523 465,
  • the infra-red dye is chosen from German patent application DE 43 31 162.
  • ID-1 is a commercial product known as CYASORB IR165, marketed by American Cyanamid Co, Glendale Protective Technologie Division, Woodbury, New-York. It is a mixture of two parts of the molecular non-ionic form (ID-1a) and three parts of the ionic form (ID-1b) (see below).
  • ID-1a molecular non-ionic form
  • ID-1b ionic form
  • the compounds are also available from Bayer AG. it must show low side absorptions in the visual and UV spectral regions. For this reason infra-red absorbing pigments such as carbon black cannot be used in the practice of this invention.
  • the concentration of the infra-red absorbing dye must be chosen so that the optical density at the emission wavelenght of the laser is at least 0.3 and most preferably at least 0.5. So the optimal concentration of the dye is dependent self-evidently on its molar extinction coefficient at this emission wavelength. Also layer compatibility and layer stability are important. The most preferred compounds are the mixture of ID-1a + ID-1b.
  • the total coverage of the barrier layer is preferably comprised between 0.5 and 7 g/m 2 .
  • the barrier layer is relatively thick its barrier action is self-evidently stronger, but the laser radiation must be stronger in order to eliminate its barrier function.
  • Substantially light-insensitive organic silver salts particularly suited for use according to the present invention in the heat-sensitive recording layer 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. Silver salts of modified aliphatic carboxylic acids with thioether group as described e.g.
  • silver salts of aromatic carboxylic acids e.g. benzoic acid, phtalic acid, terephtalic acid, salicylic acid, m-nitrobenzoic-, phenylacetic-, pyromellitic-, p-phenylbenzoic-, camphoric-, huroic-, acetamidobenzoic- and o-aminobenzoic acid, etc.
  • aromatic carboxylic acids e.g. benzoic acid, phtalic acid, terephtalic acid, salicylic acid, m-nitrobenzoic-, phenylacetic-, pyromellitic-, p-phenylbenzoic-, camphoric-, huroic-, acetamidobenzoic- and o-aminobenzoic acid, etc.
  • silver salts of mercapto group- or thione group-containing compounds e.g., 3-mercapto-4-phenyl-1,2,4-triazole, 2-mercaptobenzimidazole, etc.
  • an imino group-containing compound e.g. benzotriazole or derivatives thereof as described in GB 1,173,426 and US 3,635,719, etc.
  • the organic silver salt is silver behenate.
  • the compound is colourless, visibly stable toward light, insoluble in many volatile liquid vehicles, and moisture-resistant. It is produced in the desired physical form without difficulty and at reasonable cost.
  • the layers (2) and (4) or (3') contain a binder.
  • Suitable binders include cellulose derivatives, such as ethyl cellulose, hydroxyethyl cellulose, ethylhydroxy cellulose, ethylhydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose nitrate, cellulose acetate formate, cellulose acetate hydrogen phthalate, cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate pentanoate, cellulose acetate benzoate, cellulose triacetate; vinyl-type resins and derivatives, such as polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, copolyvinyl butyral-vinyl acetal-vinyl alcohol, polyvinyl pyrrolidone, polyvinyl acetoacetal, polyacrylamide; polymers and copolymers derived from (meth)acrylates
  • the copolymer When using copoly(stryrene-acrylonitrile) the copolymer preferably comprises at least 65 % by weight of styrene units and at least 25 % by weight of acrylonitrile units, but other comonomers can be present, e.g., butadiene, butyl acrylate and methyl methacrylate.
  • the most preferred binder for layer (2) containing the reducing agent is polyvinylalcohol.
  • layer (6') containing the reducing agent further contains a thermoadhesive polymer which itself functions as a binder and no extra binder is necessary.
  • the most preferred binder for the organic metal salt layer (4) or (3') is polyvinylbutyral, commercially known as BUTVAR, e.g. BUTVAR B79 (Monsanto Co.)
  • the acceptor layer further preferably may contain a so-called toning agent known from thermography or photothermography.
  • a toning agent or toner constitutes an alternative for the use of a reducing agent that upon oxidation forms a coloured compound the colour of which is complementary to the hue of the silver image.
  • Suitable toning agents are the phthalimides and phthalazinones within the scope of the general formulae described in US-P Re. 30,107. Further reference is made to the toning agents described in US-P's 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 : wherein
  • a toner compound particularly suited for use in combination with polyhydroxy spiro-bis-indane reducing agents like "Spirana” is 3,4-dihydro-2,4-dioxo-1,3,2H-benzoxazine described in US-P 3,951,660.
  • the layer sequence described for the mono-sheet-version is the preferred one, but, in principle, the positions of layers (2) and layers (4) can be reversed.
  • thermoadhesive polymer is present in layer (6') containing the reducing agent.
  • Useful thermoadhesive polymers are styrene-butadiene latices. These latices can contain other comonomers which improve the stabilitity of the latex, such as acrylic acid, methacrylic acid and acrylamide.
  • polymer latices include polyvinylacetate, copoly(ethylene-vinylacetate), copoly(acrylonitrile-butadiene-acrylic acid), copoly(styrene-butylacrylate), copoly(methylmethacrylate-butadiene), copoly(methylmethacrylate-butylmethacrylate), copoly(methylmethacrylate-ethylacrylate), copolyester(terephtalic acid-sulphoisophtalic acid-ethyleneglycol), copolyester(terephtalic acid-sulphoisophtalic acid-hexanediol-ethyleneglycol).
  • thermoadhesive polymers are the BAYSTAL polymer types, marketed by Bayer AG, which are on the basis of styrene-butadiene copolymers. Different types with different physical properties are available. The styrene content varies between 40 and 80 weight %, while the amount of butadiene varies between 60 and 20 weight % ; optionally a few weight % (up to about 10 %) of acrylamide and/or acrylic acid can be present. Most suited are e.g. BAYSTAL KA 8558, BAYSTAL KA 8522, BAYSTAL S30R and BAYSTAL P1800 because they are not sticky at room temperature when used in a thermoadhesive layer. Other useful polymers are the EUDERM polymers, also from Bayer AG, which are copolymers comprising n.-butylacrylate, methylmethacrylate, acrylonitrile and small amounts of methacrylic acid.
  • a stripping layer pack (2') is coated between the temporary support (1') and the layer (3') containing the organic metal salt.
  • This stripping layer pack preferably consists of two layers which have a weak adhesion to each other.
  • the first layer closest to the temporary support contains a combination of colloidal silica, such as KIESELSOL 300F (Bayer AG), and of a laponite, such as LAPONITE S (Laporte Co.), preferably in a ratio of about 75/25 ;
  • the second layer is preferably a thin protective layer (about 3 ⁇ m) composed of nitrocellulose.
  • the thermal imaging medium is exposed information-wise preferably through the coated side by means of an intense laser beam.
  • a laser can be an Ar ion laser, a HeNe laser, a Kr laser, a frequency doubled Nd-YAG laser, a dye laser emitting in the visual spectral region.
  • the radiation to heat converting compound is an infra-red absorbing compound the laser is an infra-red laser.
  • Especially preferred lasers are semiconductor diode lasers or solid state lasers such as a Nd-YAG laser emitting at 1064 nm, or a Nd-YLF laser emitting at 1053 nm..
  • diode lasers emit at 823 nm or at 985 nm.
  • a series of lasers can be used arranged in a particular array.
  • Important parameters of the laser recording are the spot diameter (D) measured at the 1/e 2 value of the intensity, the applied laser power on the film (P), and the recording speed of the laser beam (v).
  • the barrier layer is ablatively destroyed in the exposed areas, and transfer of reducing agent to the organic metal salt layer can then take place inducing chemical reduction of the organic metal salt by the reducing agent. Since however at this stage the thermal reduction of the organic silver salt is usually not complete an overall heat treatment of the exposed thermal imaging element is preferred in order to obtain a sufficient optical density.
  • An optimal overall heating lasts at least 2 s, preferably about 15 s at about 105 °C. At lower temperatures the heating time is longer and vice versa.
  • the overall heat treatment is preferably performed by pressing the thermal imaging medium against a heated metal block, e.g. an aluminium block.
  • the acceptor element is information-wise laser exposed preferably through the backside. Again, ablative destruction of the barrier layer occurs in the exposed parts. Then the donor element and the exposed acceptor element are laminated to each other so that transfer of reducing agent and partial reduction of the organic metal salt occur.
  • the lamination is carried out by bringing in contact the acceptor element and the donor element, and then introducing them into the nip af a pair of heated laminator rollers under pressure. Suitable lamination temperatures are between room temperature and 80 °C. Then the support (1') and part of the stripping layer pack (2') are removed by delamination. In the preferred embodiment described above the stripping layer pack splits between the layer containing the combination of colloidal silica plus laponite and the thin nitrocellulose protective layer.
  • the obtained heat mode image can be used as an intermediate for the UV-exposure of a UV-sensitive element, e.g., a printing plate or a silver halide contact material. In both cases the heat mode image forms an alternative for a conventional developed silver halide image-setting film.
  • the obtained heat mode image can be meant for direct visual inspection, e.g., in case of proofing purposes or in case of recording of radiographic information.
  • This example illustrates the mono-sheet version of the present invention.
  • thermal imaging media (samples 1 and 2) were built up by successive coatings.
  • the barrier layer After drying the barrier layer showed following coverages (g/m 2 ): sample 1 sample 2 nitrocellulose 0.25 1.0 hexamethylenediisocyanate 0.15 0.5 zinc octanoate 0.0012 0.0024 infra-red dye ID1a+ID1b 1.0 1.5 total dry coverage 1.4 3.0 The layer was hardened at 120 °C for 1 hour.
  • the dried layer showed following coverages : silver behenate 5.6 g/m 2 BUTVAR B79 5.2 g/m 2 succinimide 0.5 g/m 2 total dry coverage 11.3 g/m 2
  • sample 1 two different exposures, sample 2 just one
  • full area scanning with following specifications :
  • the transmission densities at Dmin and Dmax were measured using a MacBeth TD904 spectrophotometer equiped with a UV filter. Then the samples were subjected to an overall heat treatment, being a contact of the back side with an aluminium block heated at 105 °C for 15 seconds. The Dmin and Dmax values were measured again.
  • Dmin and Dmax values before and after heat treatment are represented in table 1.
  • sample before heat treatment after heat treatment ⁇ Dmax Dmin Dmax Dmin Dmax 1a 0.8 1.6 0.9 2.9 +1.3 1b 0.79 2.78 0.89 3.22 +0.44 2 1.4 3.2 1.4 3.5 +0.3
  • the three comparison samples and invention sample 1 were subjected to a thermal treatment (15 s/105 °C) without being laser exposed, and to an accelerated ageing test simulating shelf life behaviour (72 h/60°C).
  • the obtained densities (UV) are represented in table 2.
  • sample after coating after 15 s/105 °C after 72 h/60°C : ⁇ D comp.
  • B 0.17 1.49 0.25 0.08 comp.
  • C 0.71 2.43 0.98 0.27 inv. 1 0.79 0.89 0.80 0.01
  • test samples were expbsed to a full area scanning exposure (cf. invention samples 1b and 2).
  • the obtained Dmax and Dmin values (UV) are represented in table 3.
  • sample without thermal post-treatment with thermal post-treatment ⁇ Dmax Dmax Dmin ⁇ D Dmax Dmin ⁇ D comp.
  • C 1.87 0.77 1.10 2.81 2.21 0.60 0.94 inv. 1b 2.78 0.79 1.99 3.22 0.89 2.33 0.44
  • the comparison samples show a bad image differentiation.
  • the invention sample shows a good density contrast even without thermal treatment and this contrast is enhanced by the thermal treatment since Dmax is increased without significant increase in Dmin.
  • This example illustrates the two-sheet version of the present invention.
  • An acceptor element was prepared as follows. Onto a 100 pm thick subbed polyethylene terephthalate support a stripping layer pack was applied consisting of a first layer containing a mixture of KIESELSOL 300F (Bayer AG) and LAPONITE S (Laporte Co.) and a second layer composed of 3 ⁇ m thick nitrocellulose coated from a mixture of methanol/ethanol/propanol (0.85/1.0/0.15). Both layers showed a weak adhesion to each other.
  • a silver behenate layer was coated with a 100 ⁇ m knife from following composition (cf. example 1): 10.35% BUTVAR B79 (Monsanto) + 11.25% silver behenate dispersion 50 g succinimide 0.5 g solvents 49.5 g
  • the dried layer showed following coverages :
  • a barrier layer was coated with a 40 ⁇ m knife from following composition : 7.5% nitrocellulose (Wolff Walsrode E620) 1.5 g infra-red dye ID-1a (Bayer AG) 0.1 g infra-red dye ID-1b (Bayer AG) 0.15 g methanol 18.25 g
  • the dried layer showed following coverages : nitrocellulose 3.0 g/m 2 IR dyes ID-1a + ID-1b 0.5 g/m 2 total dry coverage 3.5 g/m 2
  • a donor element was prepared as follows. Onto a subbed 100 ⁇ m thick polyethylene terephthalate support a layer was coated with a 20 ⁇ m knife from the following composition : dodecyl gallate 2.4 g thermoadhesive copolyester Dynapoll L411 1.8 g thermoadhesive copolyester Dynapoll S1420 1.8 g toluene/ethylacetate 70/30 17 g
  • the dried layer showed following coverages : dodecyl gallate 2.1 g/m 2 copolyester 3.1 g/m 2 total dry coverage 5.2 g/m 2
  • the acceptor was exposed through its backside by full area scanning exposure under the following specifications : NdYLF laser emitting at 1053 nm; external drum; spot diameter 14.9 ⁇ m; drum speed 2.2 m/s; power on film 400 mW; resolution 3400 dpi (pitch 7.5 ⁇ m).
  • the donor element After exposure through the backside of the acceptor the donor element was laminated to the acceptor in a CODOR LAMIPACKER LPP650 under following conditions : 80 °C for upper and under roller; lamination speed 100 cm/min.
  • the PET support of the acceptor element was delaminated whereby separation occurred between the first layer of the stripping pack being the colloidal silica + laponite layer and the second layer of the stripping pack being the thin nitrocellulose layer.
  • the Dmax and Dmin of the remaining layer arrangement were measured and finally this layer pack subjected to an overall heat treatment, being a contact of the backside with a aluminium block heated at 105 °C for 15 seconds.
  • the Dmin and Dmax values were measured again.
  • Dmin and Dmax values before and after heat treatment are represented in table 4.
  • sample before heat treatment after heat treatment ⁇ Dmax Dmin Dmax Dmin Dmax invention 0.4 0.8 0.4 2.4 +1.6

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  • Chemical & Material Sciences (AREA)
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  • General Physics & Mathematics (AREA)
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Claims (22)

  1. Verfahren zur Erzeugung eines Bildes nach dem Wärmeverfahren mit den Schritten, in der Reihenfolge:
    (A) informationsmäßiges Belichten eines wärmeempfindlichen Bilderzeugungsmediums mit Laserstrahlen, wobei das Medium in der Reihenfolge die nachstehenden Schichten umfasst:
    (1) ein gegebenenfalls substrierter, transparenter Schichtträger,
    (2) eine Schicht mit einem Reduktionsmittel und einem Bindemittel,
    (3) eine Sperrschicht, die aufgrund des Vorhandenseins eines zersetzlichen Bindemittels aus der Reihe: ein Cellulosederivat, ein Polycarbonat, ein Polystyrol und ein Polyurethan, im Laufe der Belichtung thermisch zerstörbar ist und die das Diffundieren des Reduktionsmittels in die nachstehende Schicht (4) vor der Laserbelichtung verhindert, und die weiterhin einen Farbstoff, der Laserstrahlen in Wärme umzuwandeln vermag, enthält,
    (4) eine Schicht, die einen reduzierbaren organischen Metallsalz, ein Bindemittel und gegebenenfalls ein Tönungsmittel enthält, wobei die Laserbelichtung die Zerstörung der Sperrschicht (3) in den belichteten Bereichen und wenigstens teilweise Übertragung des Reduktionsmittels der Schicht (2) auf die Schicht (4) induziert, während in den unbelichteten Bereichen keine Zerstörung und keine Übertragung auftreten, und
    (B) gegebenenfalls Unterwerfen des belichteten wärmeempfindlichen Bilderzeugungsmediums einer totalen thermischen Behandlung.
  2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass die Sperrschicht (3) Cellulosenitrat enthält.
  3. Verfahren nach Anspruch 2, dadurch gekennzeichnet, dass das Cellulosenitrat durch eine durch eine Wärmebehandlung induzierte Vernetzungsreaktion gehärtet wird.
  4. Verfahren nach Anspruch 3, dadurch gekennzeichnet, dass die Vernetzungsreaktion in Gegenwart eines in die Sperrschicht (3) eingearbeiteten Isocyanats durchgeführt wird.
  5. Verfahren nach Anspruch 4, dadurch gekennzeichnet, dass es sich bei dem Isocyanat um Hexamethylendiisocyanat handelt.
  6. Verfahren nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass es sich bei dem reduzierbaren organischen Metallsalz der Schicht (4) um ein organisches Silbersalz handelt.
  7. Verfahren nach Anspruch 6, dadurch gekennzeichnet, dass es sich bei dem organischen Silbersalz um Silberbehenat handelt.
  8. Verfahren nach einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, dass es sich bei dem Bindemittel der Schicht (4) um Polyvinylbutyral handelt.
  9. Verfahren nach einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, dass es sich bei dem eventuellen Tönungsmittel der Schicht (4) um Succinimid handelt.
  10. Verfahren nach einem der Ansprüche 1 bis 9, dadurch gekennzeichnet, dass es sich bei dem Reduktionsmittel der Schicht (2) um einen Gallussäurenester handelt.
  11. Verfahren nach einem der Ansprüche 1 bis 10, dadurch gekennzeichnet, dass die informationsmäßige Belichtung mit Laserstrahlen unter Verwendung eines Infrarot-Lasers durchgeführt wird und dadurch, dass es sich bei der Verbindung, die Laserstrahlen in Wärme umzuwandeln vermag, um einen Infrarotabsorberfarbstoff in solcher Konzentration handelt, dass bei der Emissionswellenlänge des Infrarot-Lasers eine Dichte von zumindest 0,3 erhalten wird.
  12. Verfahren zur Erzeugung eines Bildes nach dem Wärmeverfahren mit den Schritten:
    (A') informationsmäßiges Belichten eines Empfangselements mit Laserstrahlen, wobei das Element die nachstehenden Schichten umfasst:
    (1') ein gegebenenfalls substrierter, vorläufiger transparenter Schichtträger,
    (2') ein Abziehschichtverbund,
    (3') eine Schicht, die ein reduzierbares organisches Metallsalz, ein Bindemittel und gegebenenfalls ein Tönungsmittel enthält,
    (4') eine Sperrschicht, die thermisch zerstörbar ist und einen Farbstoff, der Laserstrahlen in Wärme umzuwandeln vermag, enthält,
    indem in den belichteten Bereichen Zerstörung der Sperrschicht auftritt,
    (B') Bereitstellen eines Donatorelements, das die nachstehenden Schichten umfasst:
    (5') ein gegebenenfalls substrierter, transparenter Schichtträger,
    (6') eine Schicht, die ein Reduktionsmittel und ein (unter Wärmeeinwirkung) klebendes Polymeres enthält,
    (C') Laminieren des Empfangselements (A') auf das Donatorelement (B'), wobei die Schichten (4') und (6') einander zugewandt sind,
    (D') Entfernen des vorläufigen transparenten Schichtträgers
    (1') und zumindest eines Teils des Abziehschichtverbunds (2') durch Schichtentrennung,
    (E') Unterwerfen des sich daraus ergebenden Schichtverbunds einer totalen thermischen Behandlung.
  13. Verfahren nach Anspruch 12, dadurch gekennzeichnet, dass die Sperrschicht (4') Cellulosenitrat enthält.
  14. Verfahren nach Anspruch 12 oder 13, dadurch gekennzeichnet, dass es sich bei dem reduzierbaren organischen Metallsalz der Schicht (3') um ein organisches Silbersalz handelt.
  15. Verfahren nach Anspruch 14, dadurch gekennzeichnet, dass es sich bei dem organischen Silbersalz um Silberbehenat handelt.
  16. Verfahren nach einem der Ansprüche 12 bis 15, dadurch gekennzeichnet, dass es sich bei dem Bindemittel der Schicht (3') um Polyvinylbutyral handelt.
  17. Verfahren nach einem der Ansprüche 12 bis 16, dadurch gekennzeichnet, dass es sich bei dem eventuellen Tönungsmittel der Schicht (3') um Succinimid handelt.
  18. Verfahren nach einem der Ansprüche 12 bis 17, dadurch gekennzeichnet, dass es sich bei dem Reduktionsmittel der Schicht (6') um einen Gallussäurenester handelt.
  19. Verfahren nach einem der Ansprüche 12 bis 18, dadurch gekennzeichnet, dass die informationsmäßige Belichtung mit Laserstrahlen unter Verwendung eines Infrarot-Lasers durchgeführt wird und dadurch, dass es sich bei der Verbindung, die Laserstrahlen in Wärme umzuwandeln vermag, um einen Infrarotabsorberfarbstoff in solcher Konzentration handelt, dass bei der Emissionswellenlänge des Infrarot-Lasers eine Dichte von zumindest 0,3 erhalten wird.
  20. Verfahren nach einem der Ansprüche 12 bis 18, dadurch gekennzeichnet, dass es sich bei dem Abziehschichtverbund (2') um einen zweischichtigen Verbund handelt, dessen zwei Schichten gegeneinander eine schwache Haftung aufweisen.
  21. Verfahren nach Anspruch 20, dadurch gekennzeichnet, dass der zweischichtige Verbund eine kolloidale Kieselsäure und ein Laponit enthaltende erste Schicht umfasst, und dadurch, dass die zweite Schicht aus Cellulosenitrat besteht.
  22. Wärmeempfindliches Bilderzeugungsmedium, das in der Reihenfolge die nachstehenden Schichten umfasst:
    (1) ein gegebenenfalls substrierter, transparenter Schichtträger,
    (2) eine Schicht mit einem Reduktionsmittel und einem Bindemittel,
    (3) eine Sperrschicht, die aufgrund des Vorhandenseins eines zersetzlichen Bindemittels aus der Reihe : ein Cellulosederivat, ein Polycarbonat, ein Polystyrol und ein Polyurethan, durch die im Laufe der Belichtung erzeugten Wärme zerstörbar ist und die das Diffundieren des Reduktionsmittels in die nachstehende Schicht (4) vor der Laserbelichtung verhindert, und die weiterhin einen Farbstoff, der Laserstrahlen in Wärme umzuwandeln vermag, enthält,
    (4) eine Schicht, die einen reduzierbaren organischen Metallsalz, ein Bindemittel und gegebenenfalls ein Tönungsmittel enthält.
EP19960202650 1996-09-23 1996-09-23 Verfahren zur Herstellung eines Bildes nach dem Wärmeverfahren Expired - Lifetime EP0831364B1 (de)

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DE69631131T DE69631131D1 (de) 1996-09-23 1996-09-23 Verfahren zur Herstellung eines Bildes nach dem Wärmeverfahren
EP19960202650 EP0831364B1 (de) 1996-09-23 1996-09-23 Verfahren zur Herstellung eines Bildes nach dem Wärmeverfahren
US08/917,287 US5814430A (en) 1996-09-23 1997-08-25 Method for the formation of an improved heat mode image

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TWI400302B (zh) * 2006-03-13 2013-07-01 Hayashibara Biochem Lab Methine is a pigment and its use

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JP2004299108A (ja) * 2003-03-28 2004-10-28 Dainippon Printing Co Ltd 熱転写受像シート

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WO1990012342A1 (en) * 1989-03-30 1990-10-18 James River Paper Company, Inc. A near infrared laser absorbing coating and method for using same in color imaging and proofing
DE69215867D1 (de) * 1992-08-03 1997-01-23 Agfa Gevaert Nv Wärmeempfindliches Aufzeichnungsmaterial und Verfahren zur Herstellung von Farbbildern
JP3576553B2 (ja) * 1993-09-14 2004-10-13 アグファ−ゲヴェルト ナームロゼ ベンノートチャップ ヒートモード像を形成するための方法及び材料
US5673077A (en) * 1993-09-16 1997-09-30 Konica Corporation Process of forming a transfer-image of ablation type image-transfer recording material
EP0674217B1 (de) * 1994-03-25 2001-10-24 Agfa-Gevaert N.V. Verfahren zur Herstellung eines Bildes nach dem Wärmeverfahren
EP0706899A1 (de) * 1994-10-13 1996-04-17 Agfa-Gevaert N.V. Wärmeempfindliches Aufzeichnungselement

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TWI400302B (zh) * 2006-03-13 2013-07-01 Hayashibara Biochem Lab Methine is a pigment and its use

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