EP0510754B1 - Ecran luminescent avec couche de protection et fabrication - Google Patents

Ecran luminescent avec couche de protection et fabrication Download PDF

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Publication number
EP0510754B1
EP0510754B1 EP19920201066 EP92201066A EP0510754B1 EP 0510754 B1 EP0510754 B1 EP 0510754B1 EP 19920201066 EP19920201066 EP 19920201066 EP 92201066 A EP92201066 A EP 92201066A EP 0510754 B1 EP0510754 B1 EP 0510754B1
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Prior art keywords
coating
radiation
screen
layer
phosphor
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EP19920201066
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German (de)
English (en)
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EP0510754A1 (fr
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Philip Dooms
Jan Emiel Van Havenbergh
Jozef René Aertbelien
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Agfa Gevaert NV
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Agfa Gevaert NV
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    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K4/00—Conversion screens for the conversion of the spatial distribution of X-rays or particle radiation into visible images, e.g. fluoroscopic screens
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K4/00—Conversion screens for the conversion of the spatial distribution of X-rays or particle radiation into visible images, e.g. fluoroscopic screens
    • G21K2004/08—Conversion screens for the conversion of the spatial distribution of X-rays or particle radiation into visible images, e.g. fluoroscopic screens with a binder in the phosphor layer

Definitions

  • the present invention relates to a luminescent article comprising a coating of phosphor particles and a protective coating applied thereto.
  • penetrating radiation which is high energy radiation belonging to the class of X-rays, Gamma rays and high energy elementary particle radiation, e.g. Beta-rays, electron beam or neutron radiation.
  • penetrating radiation For the conversion of penetrating radiation into visible light and/or ultraviolet radiation luminescent substances are used called phosphors.
  • an X-ray radiograph is obtained by X-rays transmitted imagewise through an object and converted into light of corresponding intensity in a so-called intensifying screen (X-ray conversion screen) wherein phosphor particles absorb the transmitted X-rays and convert them into visible light and/or ultraviolet radiation whereto a photographic film is more sensitive than to the direct impact of the X-rays.
  • intensifying screen X-ray conversion screen
  • the light emitted imagewise by said screen irradiates a contacting photographic silver halide emulsion layer film which after exposure is developed to form therein a silver image in conformity with the X-ray image.
  • the X-ray film For use in common medical radiography the X-ray film comprises a transparant film support double-side coated with a silver halide emulsion layer. During the X-ray irradiation said film is arranged in a cassette between two X-ray conversion screens each of them making contact with their corresponding silver halide emulsion layer.
  • An autoradiograph is a photographic record formed through the intermediary of penetrating radiation emitted by radioactive material contained in an object. e.g. microtome cut for biochemical research.
  • Phosphors suitable for use in the conventional radiographic system must have a high prompt emission on X-ray irradiation and low after-glow in favour of image-sharpness.
  • an X-ray recording system wherein photostimulable storage phosphors are used that in addition to their immediate light emission (prompt emission) on X-ray irradiation, have the property to store temporarily a large part of the energy of the X-ray image which energy is set free by photostimulation in the form of light different in wavelength characteristic from the light used in the photostimulation.
  • photostimulable storage phosphors in addition to their immediate light emission (prompt emission) on X-ray irradiation, have the property to store temporarily a large part of the energy of the X-ray image which energy is set free by photostimulation in the form of light different in wavelength characteristic from the light used in the photostimulation.
  • the light emitted on photostimulation is detected photo-electronically and transformed in sequential electrical signals.
  • the basic constituents of such X-ray imaging system operating with storage phosphors are an imaging sensor containing said phosphor, normally a plate or panel, which temporarily stores the X-ray energy pattern, a scanning laser beam for photostimulation, a photo-electronic light detector providing analog signals that are converted subsequently into digital time-series signals, normally a digital image processor which manipulates the image digitally, a signal recorder, e.g. magnetic disk or tape, and an image recorder for modulated light-exposure of a photographic film or an electronic signal display unit, e.g. cathode ray tube.
  • an imaging sensor containing said phosphor normally a plate or panel, which temporarily stores the X-ray energy pattern
  • a scanning laser beam for photostimulation a photo-electronic light detector providing analog signals that are converted subsequently into digital time-series signals
  • a digital image processor which manipulates the image digitally
  • a signal recorder e.g. magnetic disk or tape
  • Both types of X-ray conversion screens generally comprise in order : a support, a layer comprising phosphor particles dispersed in a suitable binder and a protective coating coated over the phosphor containing layer to protect said layer during use.
  • the protective layer preferably has a relief structure that reduces friction as well as the tendency to show sticking phenomena with contacting materials.
  • the relief structure thus favours loading and unloading of a film from a cassette and reduces the building up of static electricity.
  • the reduction of the building up of static electricity as a consequence of friction phenomena during cassette loading and unloading is a function of the contact area and the distance between both the screens and the photographic film.
  • EP-A 0 209 358 Another reference wherein at least two different steps are required to get a protective layer comprising at least layers which regains are different under well-defined relative humidity conditions in order to get good humidity resistance is EP-A 0 209 358.
  • the outermost protective layer is coated by a Doctor coater on the first protective layer, followed by irradiation with ultraviolet ray to be cured.
  • X-ray conversion screen and phosphor refers to screens and phosphors for use in conventional screen-film combinations as well as for stimulated luminescence radiography. In the latter case improved manipulation, especially transport of the screen is required as the screen itself has to be transported from the exposure site to the unit where it has to be read out by stimulating light.
  • the protective layer by addition before coating of solid particles, e.g. polystyrene beads with a diameter of e.g. 25 ⁇ m promotes the transport characteristics of said layer but has a disadvantageous effect on abrasion resistance as these particles will be weared off.
  • the thickness of the protective layer changes together with the roughness factor and strongly depends on the viscosity of the layer which is differing as a function of the solvents used, the coating temperature and the drying conditions, being directly responsible for the penetrating depth of the particles e.g. polystyrene beads in the coated layer. As a consequence the really measured thickness depends on the amount of protrusion of said particles.
  • a luminescent article comprising a self-supporting or supported layer of phosphor particles dispersed in a resin binder having applied thereto a protective coating having an embossed structure, more particularly a protective coating having a layer thickness d comprised between 1 and 50 ⁇ m and having an embossed surface roughness R z so that the ratio between roughness R z and thickness d is at least 0.35.
  • the embossed protective layer can be provided on the phosphor layer in order to protect it against mechanical and chemical damage by the steps of
  • the correlating features of roughness and thickness of the protective coating confer to the screen of the present invention desirable and unexpected properties of ease of manipulation and excellent image sharpness.
  • the thickness d of a protective layer of the phosphor screen formed according to the present invention is in the range from 1 to 50 ⁇ m, preferably from 2 to 30 ⁇ m and more prefably from 3 to 25 ⁇ m whereby a very flexible and sufficiently abrasion-resistant coating is obtained.
  • the thickness of the protective layer can be measured from microscopic intersections or with a thickness measuring apparatus on microscale
  • roughness R z has to be determined as the arithmetic mean roughness depth value R t of five different, but subsequent measuring area; said value R t being defined as the difference in height between the highest "top” and the lowest “valley”.
  • a suitable instrument for such microscopically fine measurements is a "perthometer", by means of which the surface texture can be measured according to ANSI B46.1-1985 as published by The American Society of Mechanical Engineers.
  • R z R z : d.
  • the roughness of the topcoat layer of an intensifying screen offers the advantage that sticking phenomena between a film and an intensifying screen(s) in a cassette are substantially avoided even after intimate contact due to pressure build-up in the cassette system.
  • an X-ray conversion phosphor screen having a topcoat with embossed structure favours its practically frictionless loading and unloading of a cassette and reduces considerably the built up of static electricity.
  • the micro-channels formed by the embossed structure of the protective coating allow air to escape between phosphor screen and contacting film whereby image quality (image sharpness) is improved by better screen-film-screen contact without large air bubble inclusions.
  • the coating of the protective layer proceeds by screen-printing (silk-screen printing).
  • the screen printing process is preferred for applying paste-consistency coating compositions (viscosity at least 1000 mPa.s at coating temperature) in a fairly small thickness, e.g. coating thickness in the range of 2 to 15 ⁇ m.
  • the standard screen printing device comprises a screen printing frame wherein a piece of fabric or sieve is stretched. For printing (not for simple coating purposes) the sieve is blocked image-wise and forms a stencil. A flexible squeegee is used to force the ink (here the radiation-curable coating composition) through the sieve openings to reach the substrate whereon the ink or coating composition is deposited and after separation from the sieve is dried or hardened.
  • the protective coating composition is applied by a rotary screen printing device as has been described in detail in European Patent Application 91201009.7 filed April 26, 1991. In said document such device is illustrated schematically by the accompanying drawing.
  • the rotary screen printing device operating as coating device applies a paste-like consistency coating composition through a seamless rotary screen in the form of a sleeve.
  • a flexible squeegee blade (made from stainless steel) adjustably arranged in a clamp presses the paste through the perforated screen wall of the screen on the substrate.
  • the substrate is e.g. a film support having coated thereto a phosphor-binder layer.
  • the web-type substrate is guided by a counter pressure roller.
  • the paste-like coating composition is fed through the distribution pipe arranged inside the rotary screen which at its sleeve ends is secured to ring members freely rotating in ball bearings.
  • the screen is pneumatically tensioned in its axial direction.
  • a pump and level control means guarantee a constant paste supply.
  • thin-walled screens can be made by weaving using natural or synthetic polymer yarns or fine metal wire.
  • the screen is made by electro-deposition of metal, e.g. nickel, in a screenlike pattern.
  • screens having a screen fineness of 10 to 500 lines/cm and an open area percentage (permeability percentage) with respect to the total screen surface in the range of 5-45 % give satisfactory coating results with radiation-curable liquid coating compositions having a viscosity in the range of 1000 to 5000 mPa.s, the viscosity being lower in the case of a finer opening structure of the screen.
  • the thickness of the sieve or screen can be between 50 and 150 micron, preferably is about 100 micron.
  • Particularly smooth, thin flexible protective coatings can be prepared by the use of a screen printing device operating with screens having a thickness in the range of 10-110 ⁇ m, 3000 to 4500 holes per cm 2 and hole diameter of 80 to 40 ⁇ m.
  • Particularly useful high viscosity liquid radiation-curable coating compositions are prepared by means of addition polymerizable liquid prepolymers and/or chemically inert polymers dissolved in addition polymerizable liquid monomers up to the desired viscosity for use according to the present invention.
  • Very useful radiation curable compositions for forming a protective coating contain as primary components :
  • the usual amounts of these primary components calculated on the total coating composition are 30-100 % by weight for the prepolymer, 10-70 % by weight for the reactive diluent and 0-10 % by weight for the photoinitiator.
  • optionally minor amounts (e.g. 5 % by weight) of non-reactive organic solvent for the prepolymer may be present.
  • Suitable prepolymers for use in a radiation-curable composition applied according to the present invention are the following : unsaturated polyesters, e.g. polyester acrylates; urethane modified unsaturated polyesters, e.g. urethane-polyester acrylates.
  • unsaturated polyesters e.g. polyester acrylates
  • urethane modified unsaturated polyesters e.g. urethane-polyester acrylates.
  • Liquid polyesters having an acrylic group as a terminal group e.g. saturated copolyesters which have been provided with acryltype end groups are described in published EP-A 0 207 257 and Radiat. Phys. Chem., Vol. 33, No. 5, 443-450 (1989).
  • the latter liquid copolyesters are substantially free from low molecular weight, unsaturated monomers and other volatile substances and are of very low toxicity (ref.
  • abrasion-resistant topcoats can be obtained by the use of prepolymers also called oligomers of the class of aliphatic and aromatic polyester-urethane acrylates.
  • prepolymers also called oligomers of the class of aliphatic and aromatic polyester-urethane acrylates.
  • the structure of polyester-urethane acrylates is given in the booklet "Radiation Cured Coatings" by John R. Constanza, A.P. Silveri and Joseph A. Vona, published by Federation of Societies for Coatings Technology, 1315 Walnut St. Philadelphia, PA 19107 USA (June 1986) p. 9.
  • first tolylene 2,4-diisocyanate is used in a polyaddition reaction with aliphatic diols and the polymerizable double bond end structures are introduced by reaction of terminal isocyanate groups with 2-hydroxyethyl acrylate.
  • alkylene diisocyanate is used, e.g. 1.6-diisocyanatohexane.
  • the introduction of a plurality of acrylic double bonds per polymer chain of the prepolymer proceeds by first effecting a partial esterification of a polyol , e.g. pentaerythritol, with acrylic acid and a subsequent reaction of the still free HO-group(s) of the polyol with a polyfunctional isocyanate.
  • a polyol e.g. pentaerythritol
  • Examples of free radical polymerizable liquid monomers that preferably serve as solvent for the prepolymers and therefore are called diluent monomers are the following : methyl (metha)acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, n-hexyl acrylate, lauryl acrylate, tetrahydrofurfurylmethacrylate and the like.
  • Mono-functional diluent monomers are not necessarily applied in conjunction with unsaturated prepolymers but can be used to form a radiation-curable composition with good abrasion resistance in conjunction with saturated polyesters, e.g. polyethylene terephthalate and polyethylene isophthalate.
  • Preferred mono-functional monomers for use therewith are methyl methacrylate and tetrahydrofurfuryl methacrylate.
  • di-functional monomers examples include : 1,6-hexanediol diacrylate, 1.6-hexanediol dimethacrylate, silicone diacrylate, neopentylglycol, 1,4-butanediol diacrylate, ethyleneglycol diacrylate, polyethyleneglycol diacrylate, pentaerythritol diacrylate, divinylbenzene.
  • a difunctional acrylate e.g. hexane diol diacrylate is preferably used as reactive diluent in an amount of between 0 and 80 % by weight, preferably between 10 and 30 % by weight.
  • Suitable tri- or more-functional monomers are : trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, an acrylate of ethylenediamine, aliphatic and aromatic urethane acrylates and the monomers according to general formula (I) described in European patent application No. 91200468.6 filed March 5, 1991, wherein reference is made for the preparation of said monomers to published German patent applications Nos. 3,522,005, 3,703,080, 3,643.216, 3,703.130, 3,703,080, 3,917.320 and 3,743,728.
  • UV ultraviolet radiation
  • a photoinitiator is present in the coating composition to serve as a catalyst to initiate the polymerization of the monomers and their optional cross-linking with the pre-polymers resulting in curing of the coated protective layer composition.
  • a photosensitizer for accelerating the effect of the photoinitiator may be present.
  • Photoinitiators suitable for use in UV-curable coating compositions belong to the class of organic carbonyl compounds, for example, benzoin ether series compounds such as benzoin isopropyl , isobutylether; benzil ketal series compounds; ketoxime esters; benzophenone series compounds such as benzophenone, o-benzoylmethylbenzoate; acetophenone series compounds such as acetophenone, trichloroacetophenone, 1,1-dichloroacetophenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone; thioxanthone series compounds such as 2-chlorothioxanthone, 2-ethylthioxanthone; and compounds such as 2-hydroxy-2-methylpropiophenone, 2-hydroxy-4'-isopropyl-2-methylpropiophenone, 1-hydroxycyclohexylphenylketone; etc.
  • benzoin ether series compounds such as be
  • a particularly preferred photoinitiator is 2-hydroxy-2-methyl-1-phenyl-propan-1-one which product is marketed by E. Merck, Darmstadt, Germany under the tradename DAROCUR 1173.
  • photopolymerization initiators may be used alone or as a mixture of two or more.
  • Suitable photosensitizers are particular aromatic amino compounds as described e.g. in GB-P 1.314.556, 1,486,911. US-P 4,255,513 and merocyanine and carbostyril compounds as described in US-P 4,282,309.
  • a storage stabilizer for the radiation-curable coating composition there may be added a storage stabilizer, a colorant, and other additives, and then dissolved or dispersed therein to prepare the coating liquid for the protective layer.
  • colorants that can be used in the protective layer include MAKRAOLEX ROT EG, MAKROLEX ROT GS and MAKROLEX ROT E2G.
  • MAKROLEX is a registered tradename of Bayer AG, Leverkusen, Germany.
  • the photoinitiator which needs to be added to the coating solution will to a more or less extent also absorb the light emitted by the phosphor thereby impairing the sensitivity of the radiographic screen, particularly when a phosphor emitting UV or blue light is used.
  • a photoinitiator has to be chosen of which the absorption range overlaps to a minimum degree with the emission range of the phosphor; a preferred photoinitiator is then DAROCUR 1173 (tradename).
  • the amount of the photoinitiator used is preferably within the range of 0.01 to 5 parts by weight relative to 100 parts by weight of the prepolymer.
  • the photoinitiator is preferably used in an amount of 0.5 to 3 parts by weight and within the range of 3 to 7 times the amount of the radical-generating compound used.
  • the protective coating of the present luminescent article is given an embossed structure following the coating stage by passing the uncured or slightly cured coating through the nip of pressure rollers wherein the roller contacting said coating has a micro-relief structure, e.g. giving the coating an embossed structure so as to obtain relief parts having a height so that the ratio between roughness and thickness is at least 0.35.
  • a suitable process for forming a textured structure in a plastic coating by means of engraved chill roll is described in US-P 3,959,546.
  • the textured or embossed structure is obtained already in the coating stage by applying the paste-like coating composition with a gravure roller or screen printing device operating with a radiation-curable liquid coating composition the Hoeppler-viscosity of which at a coating temperature of 25 °C is between 450 and 20,000 mPa.s.
  • the radiation-curing is effected immediately or almost immediately after the application of the liquid coating.
  • the rheologic behaviour or flow characteristics of the radiation-curable coating composition can be controlled by means of so-called flowing agents.
  • alkylacrylate ester copolymers containing lower alkyl (C1-C2) and higher alkyl (C6-C18) ester groups can be used as shear controlling agents lowering the viscosity.
  • pigments such as colloidal silica raises the viscosity.
  • a variety of other optional compounds can be included in the radiation-curable coating composition of the present radiographic article such as compounds to reduce static electrical charge accumulation, plasticizers, matting agents, lubricants and defoamers as has been described in EP-A 0 510 753.
  • a description has also been given of the apparatus and methods for curing, as well as a non-limitative survey of X-ray conversion screen phosphors, of photostimulable phosphors and of binders of the phosphor containing layer.
  • the thickness of the phosphor layer which may differ depending on the sensitivity of the radiographic screen to radiation and the kind of the phosphor, may be within the range of from 10 to 1000 micron, preferably from 50 to 500 micron, more preferably from 150 to 250 micron.
  • Two or more phosphor layers with different thickness and/or different binder:phosphor ratio and/or different phosphor particle size may be used.
  • Radiographic screens in particular those comprising conventional non-stimulable phosphors as described above can also be in the form of gradual screens, i.e. screens having a gradual intensification along their length and/or width.
  • Graduality can be achieved by gradually increasing the thickness of the phosphor layer over the length or width of the screen or by incorporating into the protective layer or into an interlayer between the protective layer and phosphor containing layer a gradually increasing amount of dye capable of absorbing the light emitted by the phosphor.
  • graduality is obtained by halftone printing of a dye or ink composition absorbing the light emitted by the screen. By varying the screen dot size in the halftone print. i.e.
  • the halftone printing can proceed on the phosphor containing layer which thereupon is covered with the protective coating or proceeds by applying the protective coating by halftone printing, e.g. by gravure roller or silk screen printing.
  • the support material examples include cardboard, plastic films such as films of cellulose acetate, polyvinyl chloride, polyvinyl acetate, polyacrylonitrile, polystyrene, polyester, polyethylene terephthalate, polyamide. polyimide, cellulose triacetate and polycarbonate; metal sheets such as aluminum foil and aluminum alloy foil; ordinary papers: baryta paper; resin-coated papers; pigment papers containing titanium dioxide or the like; and papers sized with polyvinyl alcohol.
  • a plastic film is preferably employed as the support material.
  • the plastic film may contain a light-absorbing material such as carbon black, or may contain a light-reflecting material such as titanium dioxide or barium sulfate.
  • the former is appropriate for preparing a high-resolution type radiographic screen, while the latter is appropriate for preparing a high-sensitivity type radiographic screen.
  • Examples of preferred supports include polyethylene terephthalate, clear or blue colored or black colored (e.g., LUMIRROR C, type X30 supplied by Toray Industries, Tokyo, Japan), polyethylene terephthalate filled with TiO 2 or with BaSO 4 .
  • polyethylene terephthalate clear or blue colored or black colored (e.g., LUMIRROR C, type X30 supplied by Toray Industries, Tokyo, Japan), polyethylene terephthalate filled with TiO 2 or with BaSO 4 .
  • These supports may have thicknesses which may differ depending on the material of the support, and may generally be between 60 and 1000 micron, more preferably between 80 and 500 micron from the standpoint of handling.
  • a phosphor coating composition was prepared by intimately mixing the following components as described below:
  • the green light emitting terbium doped gadolinium oxysulphide phosphor (80 %) was predispersed in a low viscous presolution (20 %) of binder.
  • the presolution consisted of 7 % by weight of polyethyl acrylate, 18 % of ethyl acetate, 50 % of methyl ethyl ketone, 24.5 % of methyl glycol and 0.5 % of GAFAC RM 610 (tradename).
  • polyethyl acrylate binder and ethyl acetate solvent were added to the phosphor predispersion to obtain a solution with a solid content of 70 %, with 89 % of phosphor with respect to 11 % of binder.
  • Said composition was doctor blade coated onto a subbed 200 ⁇ m thick polyethylene terephthalate support at a phosphor coverage of 60 g/m 2 and dried. It has to be said that every known phosphor or phosphor mixture, whether conventional or photostimulable, could have been coated as this layer.
  • the radiation curable topcoat-layer composition was prepared by mixing in a 60/40 ratio a mixture of prepolymers with the diluent monomer hexane diol diacrylate (HDDA).
  • the photoinitiator DAROCUR 1173 (tradename) was added in a 5 % ratio with respect to the coating composition.
  • the radiation curable coating composition had a Hoeppler viscosity of 1000 mPa.s at 20 °C, the coating temperature.
  • the coating by screen printing was carried out with a STORK (tradename) printing system PD-IV operating with a cylindrical Stork DLH sieve used as a template and having a circumference of 64 cm (mesh 155, thickness 110 micron, open area 6-8 %, diameter of the circular openings 43-49 micron).
  • the obtained coating thickness d was 8-10 ⁇ m and the printing proceeded at a speed of 4 m/min.
  • the doctor blade was made of stainless steel with a length of 20 mm and a thickness of 0.2 mm. Further adjustments of the coating machine were: a pressure of the doctor blade of 6 units, and a height of said doctor blade of 21 units.
  • the applied radiation curable coating composition was cured by UV radiation using a Labcure Unit supplied by Technigraf GmbH, Grävenwiesbach, W. Germany (air cooling, energy output of 80 W/cm, velocity 4 m/min, distance UV source-substrate 11 cm).
  • a series of screens were made varying in roughness R z from 1 to 8 ⁇ m defined from "perthometer” measurements cited hereinbefore. To obtain said series variations were applied to rheology determining parameters like the pressure and the height of the doctor blade, the amounts and the concentrations of the solvents added to the phosphor predispersion, the squeegee pressure and the coating velocity.
  • Transport and manipulation characteristics can be simulated making use of a vacuum suction experiment. Principally a rubber sucking-cup is put on the X-ray conversion screen creating underpressure between the sucking-cup and the screen surface by vacuum suction. Experimentally the time can be measured between the moment that the vacuum suction has been ended and the moment that the contact between the screen and the cup has been broken. Use can be made therefore of the "Automatic Bekk Smoothness Tester, code 131ED" from Büchel-Van Der Korput BV (Veenendaal, Holland), allowing to register the relationship between the contact time t and the roughness of the screen R z as has been illustrated in Fig. 1. Fig.
  • the overall thickness of 8-10 ⁇ m for the protective layer is in favour of image-sharpness.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Paints Or Removers (AREA)
  • Luminescent Compositions (AREA)
  • Conversion Of X-Rays Into Visible Images (AREA)

Claims (11)

  1. Article luminescent comprenant une couche autoporteuse ou supportée de particules de luminophore dispersées dans un liant résineux, sur laquelle a été appliqué un revêtement protecteur ayant une épaisseur de couche d comprise entre 1 et 50 µm et ayant une rugosité de surface bosselée Rz telle que le rapport entre la rugosité Rz et l'épaisseur d, étant appelé VRd, soit d'au moins 0,35.
  2. Article luminescent selon la revendication 1, dans lequel ladite couche protectrice possède une épaisseur d comprise entre 2 et 30 µm.
  3. Article luminescent selon la revendication 1, dans lequel ladite couche protectrice possède une épaisseur d comprise entre 3 et 25 µm.
  4. Article luminescent selon les revendications 1 à 3, dans lequel ladite couche protectrice est un revêtement durci par un rayonnement.
  5. Procédé de fabrication d'un article luminescent selon l'une quelconque des revendications 1 à 4, comprenant les étapes consistant à
    (1) appliquer, sur ladite couche contenant le luminophore, une composition liquide durcissable par un rayonnement, ayant, à la température de l'application, une viscosité d'au moins 450 mPa.s, mesurée à l'aide d'un viscosimètre Hoeppler, qui ne pénètre pas à un degré substantiel dans la couche contenant le luminophore,
    (2) donner au revêtement une structure bosselée, et
    (3) durcir ledit revêtement sous l'action d'un rayonnement.
  6. Procédé selon la revendication 5, dans lequel ladite composition de revêtement liquide durcissable sous l'action d'un rayonnement possède une viscosité dans la gamme de 450 à 20 000 mPa.s à 25°C, mesurée à l'aide d'un viscosimètre Hoeppler.
  7. Procédé selon la revendication 5 ou 6, dans lequel ladite composition de revêtement liquide durcissable sous l'action d'un rayonnement est appliquée par sérigraphie.
  8. Procédé selon la revendication 7, dans lequel ladite sérigraphie est réalisée à l'aide d'un dispositif de sérigraphie rotatif.
  9. Procédé selon l'une quelconque des revendications 5 à 8, dans lequel le durcissement sous l'action d'un rayonnement est fait par un rayonnement ultraviolet ou par un rayonnement de faisceau électronique.
  10. Procédé selon l'une quelconque des revendications 5 à 9, dans lequel la rugosité Rz est obtenue par passage de la trame munie d'un revêtement protecteur non durci ou seulement légèrement durci dans la zone de pincement de rouleaux de pression dont le rouleau en contact avec ledit revêtement possède une structure à microrelief.
  11. Procédé selon l'une quelconque des revendications 5 à 9, dans lequel la rugosité Rz est obtenue lors de l'étape d'enduction par application de la composition de revêtement au moyen d'un rouleau d'héliogravure ou d'un dispositif d'impression sérigraphique.
EP19920201066 1991-04-26 1992-04-15 Ecran luminescent avec couche de protection et fabrication Expired - Lifetime EP0510754B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP19920201066 EP0510754B1 (fr) 1991-04-26 1992-04-15 Ecran luminescent avec couche de protection et fabrication

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
EP91201009 1991-04-26
EP91201009 1991-04-26
EP91203156 1991-12-03
EP91203156 1991-12-03
EP19920201066 EP0510754B1 (fr) 1991-04-26 1992-04-15 Ecran luminescent avec couche de protection et fabrication

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EP0510754A1 EP0510754A1 (fr) 1992-10-28
EP0510754B1 true EP0510754B1 (fr) 1997-01-15

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EP19920201066 Expired - Lifetime EP0510754B1 (fr) 1991-04-26 1992-04-15 Ecran luminescent avec couche de protection et fabrication

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EP (1) EP0510754B1 (fr)
JP (1) JPH05247456A (fr)
DE (1) DE69216678T2 (fr)

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Publication number Priority date Publication date Assignee Title
US6815092B2 (en) * 2001-12-05 2004-11-09 Agfa-Gevaert Radiation image storage panel
EP1318525A3 (fr) * 2001-12-05 2007-03-28 Agfa-Gevaert Ecran pour l'enregistrement d'une image obtenue par rayonnement
JP4208790B2 (ja) 2004-08-10 2009-01-14 キヤノン株式会社 放射線検出装置の製造方法
EP1884958B1 (fr) 2006-07-31 2012-11-21 Agfa HealthCare NV Compositions de polymères et leurs utilisations comme surcouches pour des écrans ou panneaux au phosphore ou des écrans ou panneaux scintillateurs
EP1884959B1 (fr) * 2006-07-31 2011-09-14 Agfa HealthCare NV Panneaux ou écrans phosphorescents ou scintillants avec une surcouche
KR101931621B1 (ko) * 2012-05-22 2018-12-24 나노코 테크놀로지스 리미티드 고 반사 물질을 이용한 양자 수율 향상
FR3022555B1 (fr) * 2014-06-23 2017-12-22 Saint-Gobain Cristaux Et Detecteurs Materiau luminescent a couche photonique texturee
ES2867807T3 (es) * 2017-04-24 2021-10-20 Igm Group B V Proceso para la preparación de cetonas a-funcionalizadas

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DE3402503A1 (de) * 1984-01-25 1985-07-25 Siemens AG, 1000 Berlin und 8000 München Roentgenverstaerkerfolie
JPS6215500A (ja) * 1985-07-15 1987-01-23 コニカ株式会社 放射線画像変換パネル

Also Published As

Publication number Publication date
DE69216678D1 (de) 1997-02-27
JPH05247456A (ja) 1993-09-24
DE69216678T2 (de) 1997-07-24
EP0510754A1 (fr) 1992-10-28

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