WO1998047718A1 - Production d'images demi-ton par transfert de film par laser sur un recepteur texture - Google Patents

Production d'images demi-ton par transfert de film par laser sur un recepteur texture Download PDF

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Publication number
WO1998047718A1
WO1998047718A1 PCT/US1998/008095 US9808095W WO9847718A1 WO 1998047718 A1 WO1998047718 A1 WO 1998047718A1 US 9808095 W US9808095 W US 9808095W WO 9847718 A1 WO9847718 A1 WO 9847718A1
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WIPO (PCT)
Prior art keywords
receptor
colorant
layer
sheet
transfer
Prior art date
Application number
PCT/US1998/008095
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English (en)
Inventor
Ranjan C. Patel
John Souter
Gregory L. Zwadlo
Mark R. I. Chambers
Jonathan C. Vogel
Original Assignee
Minnesota Mining And Manufacturing Company
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Filing date
Publication date
Application filed by Minnesota Mining And Manufacturing Company filed Critical Minnesota Mining And Manufacturing Company
Priority to AU72538/98A priority Critical patent/AU7253898A/en
Publication of WO1998047718A1 publication Critical patent/WO1998047718A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
    • B41M5/52—Macromolecular coatings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M7/00—After-treatment of prints, e.g. heating, irradiating, setting of the ink, protection of the printed stock
    • B41M7/0027—After-treatment of prints, e.g. heating, irradiating, setting of the ink, protection of the printed stock using protective coatings or layers by lamination or by fusion of the coatings or layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
    • B41M5/34—Multicolour thermography
    • B41M5/345—Multicolour thermography by thermal transfer of dyes or pigments
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
    • B41M5/382—Contact thermal transfer or sublimation processes
    • B41M5/392—Additives, other than colour forming substances, dyes or pigments, e.g. sensitisers, transfer promoting agents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
    • B41M5/382—Contact thermal transfer or sublimation processes
    • B41M5/392—Additives, other than colour forming substances, dyes or pigments, e.g. sensitisers, transfer promoting agents
    • B41M5/395—Macromolecular additives, e.g. binders
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
    • B41M5/40—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used characterised by the base backcoat, intermediate, or covering layers, e.g. for thermal transfer dye-donor or dye-receiver sheets; Heat, radiation filtering or absorbing means or layers; combined with other image registration layers or compositions; Special originals for reproduction by thermography
    • B41M5/42—Intermediate, backcoat, or covering layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
    • B41M5/40—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used characterised by the base backcoat, intermediate, or covering layers, e.g. for thermal transfer dye-donor or dye-receiver sheets; Heat, radiation filtering or absorbing means or layers; combined with other image registration layers or compositions; Special originals for reproduction by thermography
    • B41M5/42—Intermediate, backcoat, or covering layers
    • B41M5/423—Intermediate, backcoat, or covering layers characterised by non-macromolecular compounds, e.g. waxes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
    • B41M5/40—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used characterised by the base backcoat, intermediate, or covering layers, e.g. for thermal transfer dye-donor or dye-receiver sheets; Heat, radiation filtering or absorbing means or layers; combined with other image registration layers or compositions; Special originals for reproduction by thermography
    • B41M5/46—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used characterised by the base backcoat, intermediate, or covering layers, e.g. for thermal transfer dye-donor or dye-receiver sheets; Heat, radiation filtering or absorbing means or layers; combined with other image registration layers or compositions; Special originals for reproduction by thermography characterised by the light-to-heat converting means; characterised by the heat or radiation filtering or absorbing means or layers
    • B41M5/465—Infra-red radiation-absorbing materials, e.g. dyes, metals, silicates, C black
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
    • B41M5/52—Macromolecular coatings
    • B41M5/5218—Macromolecular coatings characterised by inorganic additives, e.g. pigments, clays
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
    • B41M5/52—Macromolecular coatings
    • B41M5/5227—Macromolecular coatings characterised by organic non-macromolecular additives, e.g. UV-absorbers, plasticisers, surfactants
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
    • B41M5/52—Macromolecular coatings
    • B41M5/5254—Macromolecular coatings characterised by the use of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds, e.g. vinyl polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
    • B41M5/52—Macromolecular coatings
    • B41M5/529—Macromolecular coatings characterised by the use of fluorine- or silicon-containing organic compounds

Definitions

  • This invention relates to a method of imaging in which a thermofusible colorant is transferred from a donor to a receptor under the influence of laser radiation.
  • the invention relates to such an imaging method in which the receptor comprises a surface texture that is optimized for the "footprint" of the exposing laser.
  • the donor elements typically comprise a support bearing, in one or more coated layers, an absorber for the laser radiation, a transferable colorant (e.g., one or more dyes or pigments) and one or more binder materials.
  • a transferable colorant e.g., one or more dyes or pigments
  • binder materials e.g., one or more binder materials.
  • the process is ideally suited to the output of digitally stored image information, and has the additional benefits of not requiring chemical processing, and not employing materials that are sensitive to normal white light.
  • JP-46-3710 which was filed in 1966, discloses transfer of colorant from a donor to a receptor by a " sputtering" process mediated by laser exposure. Coatings of printing ink on plastic film are quoted as highly suitable donor sheets.
  • a paper published in 1970 (Applied Optics. 9 (No. 10), pp. 2260- 2265) distinguishes two modes of laser mass transfer, namely a less energetic mode in which transfer occurs in a fluid state (i.e., melt transfer), and a more energetic mode in which transfer occurs by an explosive force, as a result of generation and rapid expansion of gases at the substrate-coating interface (i.e., ablation transfer). This distinction is also recognized consistently by later authors.
  • US-A-5,156,938, US-A-5,171,650, US-A-5,516,622 and US-A- 5,518,861 all refer to ablation transfer as a process distinct from melt transfer, and emphasize its explosive nature.
  • the first two patents in particular emphasize the use of thermally degradable materials to assist with the transfer process.
  • Many other patents, such as US-A-3, 962,513, refer to the use of nitrocellulose or " self-oxidizing" binders in ablation transfer.
  • Transfer of the colorant layer in the form of a coherent film enables dots or pixels to be transferred to the receptor with excellent edge definition. Furthermore, the curing that occurs in the course of the transfer leads to an image of enhanced durability with excellent overprint characteristics, i.e., it is possible to transfer second and subsequent images to a common receptor without damaging the first image transferred thereto. Both of these factors are important in the successful development of a digital half-tone imaging system based on laser-induced colorant transfer. Under carefully controlled laboratory conditions, small-area images of excellent quality are formed by the LIFT process using conventional smooth receptors such as resin-coated paper.
  • the imaging is carried out in a less well-controlled environment, the image quality is found to deteriorate markedly, with voids appearing (apparently) at random in the transferred image.
  • the problem may be traced to the presence of dust particles on the surfaces of the donor and receptor. Such particles not only prevent effective contact of the donor with the receptor in their immediate vicinity, but also adversely affect the focusing of the laser by causing bumps or undulations in the absorbing layer, so that even small dust particles can give rise to significant "dropouts.”
  • the problem is particularly acute in the case of large area images (e.g., of A2 size), where the likelihood of attracting dust on to the surfaces of the sheets is greater due to the triboelectric charging that inevitably results from the handling of such large sheets.
  • particulate matter in adhesive layers for anti -blocking characteristics is known.
  • a specific example of using organic polymeric beads with a narrow molecular weight distribution in an adhesive layer of a surprint color proof is described in US-A-4,885,225.
  • the size of the polymeric beads is kept small enough to become encapsulated into the adhesive when the proofing film is laminated to an opaque substrate; and thus, the beads have little or no effect on the visual properties of the final imaged proof.
  • Organic polymerio beads dispersed in a water-based receptive coating have also been shown to be useful in electrostatic transparencies imaged in plain paper copiers. Specific examples of this application are described in US- A-5,310,595 and US-A-4,869,955. In these applications the image is transferred onto the receptive layer containing the polymeric beads.
  • textured surface between donor and receptor, the texture being generated by embossing or other suitable means not involving the use of added particulates, is disclosed in US-A-5,254,514. It is noteworthy that many of these patents describe the primary purpose of the beads or other spacing means as being to prevent adhesion of donor layer to receptor layer.
  • the APPROVAL digital color proofing system commercially available from Kodak, is based on dye sublimation transfer, and utilizes a receptor sheet comprising beads in the receptor layer. Microscopic analysis indicates that the beads are about 20 ⁇ m in diameter and are present at a coverage of no more than about 100 beads per mm 2 . Spacer beads have also been advocated for use in laser mass transfer imaging, but only in the context of ablation transfer.
  • the objective is to transfer dyes in a vaporized state without co-transfer of binder. Preventing the donor layer from actually contacting the receptor layer over most of its area is therefore a logical approach.
  • an explosive expansion of gases propels the colorant towards the receptor, and so a gap between the donor and receptor in no way hinders the transfer process. Indeed, by allowing expansion to proceed preferentially in the forward direction, the tendency to expand sideways (causing image spread) is minimized.
  • said receptor sheet comprises a support having a textured receptor surface comprising a plurality of protrusions projecting above the plane of the outer surface of said receptor by an average distance of no greater than about 8 ⁇ m (preferably, at least 1 ⁇ m), there being on average at least 1 of such protrusions per area of A ⁇ m 2 .
  • Steps (a) to (c) of the imaging method are preferably repeated one or more times using a different colorant donor sheet comprising a different colorant in each case, but using the same receptor sheet in each case.
  • the image- bearing receptor sheet is optionally subjected to a lamination process in which the receptor layer, together with the image residing therein, is transferred to another support.
  • the outer surface of the receptor refers to the surface of the receptor layer furthest from the support of the receptor, i.e., the surface of the receptor which is presented to the donor.
  • the reference to the plane of the outer surface of the receptor refers to the plane of surface of the layer between the protrusions.
  • the thermofusible colorant layer is one that melts or softens under the action of heat.
  • melt transfer in which the colorant layer must melt or soften and then wet and adhere to the receptor layer, suggests that spacer beads would be detrimental to the process.
  • the melt transfer process necessarily involves intimate contact of donor layer with receptor layer. Spacing beads have a long history of use in the imaging art generally, and the field of laser induced colorant transfer in particular, for the precise purpose of preventing such a contact occurring.
  • the optimum size and concentration of beads or other particles was found to depend on the dimensions of the footprint of exposing laser, i.e., the diameter of the illuminated spot at the plane of the colorant layer, which determines the minimum size of dot or pixel which can be transferred from donor to receptor. This is typically in the range of about 5 ⁇ m to about 50 ⁇ m, but may be different for different designs of imaging engine.
  • the Presstek PEARLSETTER imager has a pixel size of about 30 ⁇ m diameter
  • the Creo TRENDSETTER device has a pixel size of about 8 ⁇ m.
  • the concentration of beads or other inert particles in the receptor layer should be sufficient to provide on average at least 1 point of contact per pixel between the donor and receptor layers, preferably at least 2 points of contact. Thus, loadings of the order of about 5x10 2 to 10 5 particles per mm 2 are typically found to be useful.
  • the beads or other particles may be of essentially uniform size (i.e., a monodisperse population), or may vary in size. Dispersions of inorganic particles such as silica generally have a range of particle sizes, whereas monodisperse suspensions of polymer beads are readily available. Whichever type of population is used, the particles should not project above the plane of the surface of the receptor layer by more than about 8 ⁇ m on average, but should preferably project above said plane by at least about 1 ⁇ m, and more preferably at least about 3 ⁇ m.
  • the composition of the polymeric beads is generally chosen such that substantially all of the visible wavelengths (400 nm to 700 nm) are transmitted through the material to provide optical transparency.
  • Non-limiting examples of polymeric beads that have excellent optical transparency include polymethylmethacrylate and polystyrene methacrylate beads, described in US-A-2, 701,245; and beads comprising diol dimethacrylate homopolymers or copolymers of these diol dimethacrylates with long chain fatty alcohol esters of methacrylic acid and/or ethylenically unsaturated comonomers, such as stearyl methacrylate/hexanediol diacrylate crosslinked beads, as described in US-A-5,238,736 and US-A-5,310,595.
  • the shape, surface characteristics, concentration, size, and size distribution of the polymeric beads are selected to optimize performance of the transfer process.
  • the smoothness of the bead surface and shape of the bead may be chosen such that the amount of reflected visible wavelenghts (400 nm to 700 nm) of light is kept to a minimum. This may or may not be an issue depending upon the actual substrate used. For example, if the color proof is formed on a transparent substrate, the haze introduced by the presence of the beads may be effected by the color.
  • the shape of the beads is preferably spherical, oblong, ovoid, or elliptical. In some constructions, it is advantageous to add two distinct sets of beads with different average sizes. This allows the flexibility to balance haze with slip or separation characteristics.
  • the optimum particle size depends on a number of factors, including the thickness of the receptor layer, the thickness of the colorant layer to be transferred, and the number of colorant layers to be transferred to a given receptor.
  • the projections provided by the particles must be great enough not to be obscured by the first layer(s) transferred thereto. If the average projection is significantly greater than about 8 ⁇ m, however, transfer of the colorant layer as a coherent film becomes impossible, and the quality of the transferred image deteriorates markedly.
  • polydisperse populations of particles such as silica particles
  • excellent results have been obtained when the largest of said particles project above the plane of the receptor layer by about 4 ⁇ m and provide on average at least 1 point of contact per pixel between the donor and receptor layers, with at least 2 (preferably at least 4) smaller particles also present per pixel.
  • Good results have also been obtained using essentially monodisperse populations of polymer beads projecting about 4 ⁇ m above the plane of the receptor layer and providing on average at least 1 point of contact per pixel between the donor and receptor layers.
  • Receptor elements used in the invention generally comprise a support sheet bearing a receptor layer containing the beads or other inert particles.
  • the receptor layer also contains a bleaching agent capable of bleaching the infrared dye which typically co-transfers with the colorant.
  • the composition of the support sheet is not critical, and essentially any sheet-form material may be used, with flexible materials such as paper or plastic film being preferred.
  • the receptor layer is typically a thermoplastic polymer layer of about 1 ⁇ m to about 10 ⁇ m, preferably about 1.5 ⁇ m to about 5 ⁇ m, in thickness.
  • a wide variety of polymers may be employed, provided that a clear, colorless, nontacky film is produced. Within these constraints, selection of polymers for use in the receptor layer is governed largely by compatibility with the colorant intended to be transferred to the receptor, and with the bleaching agent, if used.
  • Vinyl polymers such as poly vinyl butyral (e.g., BUTVAR B-76 supplied by Monsanto), vinyl acetate/vinyl pyrrolidone copolymers (e.g., E735, E535 and E335 supplied by GAF) and styrene butadiene polymers (e.g., PLIOLITE S5A supplied by Goodyear) have been found to be particularly suitable.
  • the receptor layer may be coated directly on the support sheet, or there may be one or more underlayers separating the receptor layer from the support sheet.
  • a particularly advantageous construction is a support sheet coated with a release layer followed by the receptor layer, as this allows the receptor layer (after an image has been transferred thereto) to be transferred to another substrate by a process of lamination followed by peeling of the support sheet.
  • release layers for this purpose is well known in the art, for example, US-A-5,053,381, US-A- 5,126,760 and US-A-5,278,576, and suitable materials include fluorinated polymers, silicones, etc.
  • the receptor layer additionally comprises one or more compounds capable of bleaching the infrared absorber associated with the colorant layer, as disclosed in EP-A-0675003 and British Patent Application No. 9617416 filed Aug. 20, 1996.
  • Preferred bleach agents include amines, such as, diphenylguanidine and salts thereof. The bleach agents are typically used at a loading equivalent to about 5 wt% to about 20 wt% of the receptor layer.
  • a suitable receptor layer comprises PLIOLITE S5A containing diphenylguanidine as bleach agent (10 wt% of total solids) and beads of poly(stearyl methacrylate) (8 ⁇ m diameter) (about 5 wt% of total solids), coated at about 5.9 g/m 2 .
  • a particularly preferred receptor layer is obtained by coating the following formulation from methylethyl ketone (18 wt%) to provide a dry coating weight of 400 mg/ft 2 (4.3 g/m 2 ):
  • the receptor surface may be physically textured to provide the required protrusions.
  • Metal surfaces such as aluminum, may be textured by graining and anodizing. Other textured surfaces may be obtained by microreplication techniques, such as those disclosed in EP-A-382420.
  • the extent of the protrusions on the receptor surface may be measured, for example, by interferometry or by examination of the surface using an optical or electron microscope.
  • Colorant donor sheets suitable for use in the invention comprise a support and a thermofusible colorant transfer layer comprising a binder, a colorant and an absorber.
  • the binder is chosen from transparent, film-forming resins, soluble in common organic solvents, which melt or soften at moderately elevated temperatures but do not decompose catastrophically when heated at such temperatures that occur during laser address and film transfer.
  • the binder resin contains functional groups which enable it to participate in curing reactions with other constituents of the colorant layer.
  • a wide variety of commonly-available resins are potentially suitable, and a preferred material is BUTVAR B-76, available from Monsanto.
  • the absorber used in the invention is a material which will absorb IR or light generating to heat.
  • absorber i.e., light-to-heat converter
  • any dye or pigment may be used, providing it absorbs efficiently at the output wavelength of the intended laser imaging source.
  • the preferred class of infrared dyes is that of the tetraarylpolymethine (TAPM) dyes, as disclosed in EP-A-0675003.
  • TAPM tetraarylpolymethine
  • Ar' to Ar 4 are aryl groups which may be the same or different, and X is an anion.
  • tertiary amino groups Preferably, from one to three of the said aryl groups bear a tertiary amino substituent, preferably in the 4-position. Most preferably, at least one but no more than two of said aryl groups bear a tertiary amino substituent.
  • Ar' or Ar and Ar 3 or Ar 4 bear the tertiary amino substituent.
  • tertiary amino groups include dialkylamino groups (such as dimethylamino, diethylamino, etc.), diarylamino groups (such as diphenylamino), alkylarylamino groups (such as N-methylanilino), and heterocyclic groups such as pyrrolidino, morpholino or piperidino.
  • the tertiary amino group may form part of a fused ring system, e.g., one or more of Ar 1 to Ar 4 may represent a julolidine group.
  • the aryl groups represented by Ar 1 to Ar 4 may comprise phenyl, naphthyl, or other fused ring systems, but phenyl rings are preferred.
  • substituent which may be present on the rings include alkyl groups (preferably of up to 10 carbon atoms), halogen atoms (such as Cl, Br, etc.), hydroxy groups, thioether groups and alkoxy groups.
  • Substituents which donate electron density to the conjugated system, such as alkoxy groups are particularly preferred.
  • Substituents, especially alkyl groups of up to 10 carbon atoms or aryl groups of up to 10 ring atoms may also be present on the polymethine chain.
  • the anion X is derived from a strong acid (e.g., HX should have a pKa of less than 3, preferably less than 1).
  • Suitable identities for X include ClO 4 , BF 4 , CF 3 SO 3 , PF 6 , AsF 6 SbF 6 , and perfluoroethylcyclo-hexylsulphonate.
  • Preferred dyes of this class include:
  • the relevant dyes may be synthesised by known methods, e.g., by conversion of the appropriate benzophenones to the corresponding 1,1- diarylethylenes (by the Wittig reaction, for example), followed by reaction with a trialkyl orthoester in the presence of strong acid HX.
  • the infrared absorber should be present in sufficient quantity to provide a transmission optical density of at least 0.75, preferably at least 1.0.
  • any colorant may be incorporated in the colorant transfer layer providing the colorant will not sublime under imaging conditions.
  • Suitable colorants include soluble or insolube dyes, dispersions of pigment particles, or mixtures of both dyes and pigments, but pigment dispersions are preferred. Pigments or mixtures of pigments may be employed so as to impart a particular color to the transfer layer, or to confer particular properties thereto such as magnetic properties, pearlescence, opalescence, fluorescence, etc.
  • Blends of pigments as commonly used in the proofing industry and in printing inks are particularly preferred (preferably matching the color references provided by the International Prepress Proofing Association, known as the SWOP color references), and are most preferably used in conjunction with a dispersant, such as DISPERBYK- 161, available from BYK-Chemie.
  • the colorant transfer layer advantageously may comprise a latent curing agent as disclosed in British Patent Application No. 9617414.9 entitled " Crosslinkable Media Imageable by Laser Irradiation,” filed August 20, 1996.
  • Preferred latent curing agents satisfy the formula:
  • R 1 is H, an alkyl group, a cycloalkyl group, or an aryl group; each R 2 is independently an alkyl group or an aryl group; each R 3 is independently an alkyl group or an aryl group; and R 4 is an aryl group.
  • Such compounds are believed to be oxidized during laser exposure to the corresponding pyridinium salts, which can undergo transesterification reactions with hydroxy-functional resins, leading to crosslinking. The process is facilitated by the use, as laser absorber, of cationic dyes such as the above- described TAPM dyes.
  • Preferred latent curing agents include:
  • the colorant transfer layer comprises a fluorochemical additive in addition to a dispersion of pigment particles, as disclosed in EP-A-0602893.
  • a fluorochemical additive in addition to a dispersion of pigment particles, as disclosed in EP-A-0602893.
  • Preferred fluorochemical additives comprise a perfluoroalkyl chain of at least six carbon atoms attached to a polar group such as carboxylic acid, ester, sulphonamide, etc. Minor amounts of other ingredients may optionally be present in the colorant transfer layer, such as surfactants, coating aids, etc., in accordance with known techniques.
  • Colorant transfer layers suitable for use in the invention are formed as a coating on a support.
  • the support may be any sheet- form material of suitable thermal and dimensional stability, and for most applications should be transparent to the exposing laser radiation.
  • Polyester film base of about 20 ⁇ m to about 200 ⁇ m thickness, is most commonly used, and if necessary may be surface-treated so as to modify its wettability and adhesion to subsequently applied coatings. Such surface treatments include corona discharge treatment, and the application of subbing layers or release layers.
  • the relative proportions of the components of the colorant transfer layer may vary widely, depending on the particular choice of ingredients and the type of imaging required.
  • Preferred pigmented colorant transfer layers for use in the invention have the following approximate composition (in which all percentages are by weight):
  • hydroxy-functional film-forming resin e.g., BUTVAR B76 35 to 65%
  • latent curing agent e.g., C Constant C 2 or C 3 .
  • infrared dye e.g., D, or D 2
  • fluorochemical additive e.g., a perfluoroalkylsulphonamide 1 to 10%
  • Thin coatings e.g., of less than about 3 ⁇ m dry thickness
  • Transfer occurs with high sensitivity and resolution, and heating the transferred image for relatively short periods (e.g., one minute or more) at temperatures in excess of about 120°C causes curing and hardening, as well as bleaching of the infrared dye, and hence an image of enhanced durability, uncontaminated by unwanted absorptions is obtained.
  • Colorant donor elements for use in the invention are readily prepared by dissolving or dispersing the various components in a suitable organic solvent and coating the mixture on a film base.
  • Pigmented transfer media are most conveniently prepared by predispersing the pigment in the binder resin in roughly equal proportions by weight in the presence of a suitable dispersing aid, in accordance with standard procedures used in the color proofing industry, thereby providing pigment " chips.” Milling the chips with solvent provides a millbase, to which further resin, solvents, etc., are added as required to give the final coating formulation. Any of the standard coating methods may be employed, such as roller coating, knife coating, gravure coating, bar coating, etc., followed by drying at moderately elevated temperatures. The procedure for imagewise transfer of colorant from donor to receptor is conventional. The two elements are assembled in intimate face-to- face contact, e.g., by vacuum hold down, and scanned by a suitable laser.
  • the assembly may be imaged by any of the commonly used lasers, depending on the absorber used, but address by near infrared emitting lasers such as diode lasers and YAG lasers, is preferred.
  • Any of the known scanning devices may be used, e.g., flat-bed scanners, external drum scanners or internal drum scanners.
  • the assembly to be imaged is secured to the drum or bed, e.g., by vacuum hold-down, and the laser beam is focused to a spot, e.g., of about 10 ⁇ m to about 50 ⁇ m diameter, on the IR-absorbing layer of the donor- receptor assembly. This spot is scanned over the entire area to be imaged while the laser output is modulated in accordance with electronically stored image information.
  • Two or more lasers may scan different areas of the donor receptor assembly simultaneously, and if necessary, the output of two or more lasers may be combined optically into a single spot of higher intensity.
  • Laser address is normally from the donor side, but may be from the receptor side if the receptor is transparent to the laser radiation.
  • the image residing on the receptor after peeling the donor sheet from the receptor may be further cured and/or bleached by subjecting it to heat treatment, preferably at temperatures in excess of about 120°C.
  • heat treatment preferably at temperatures in excess of about 120°C.
  • This may be carried out by a variety of means, such as storage in an oven, hot air treatment, contact with a heated platen or passage through a heated roller device.
  • multicolor imaging where two or more monochrome images are transferred sequentially to a common receptor, it is more convenient to delay the heating step until all the separate colorant transfer steps have been completed, then provide a single heat treatment for the composite image.
  • the receptor element of the invention to which a colorant image is initially transferred, is not the final substrate on which the image is viewed.
  • US-A-5, 126,760 discloses thermal transfer of a multicolor image to a first receptor, with subsequent transfer of the composite image to a second receptor for viewing purposes. If this technique is employed in the practice of the present invention, curing and/or bleaching of the image may conveniently be accomplished in the course of the transfer to the second receptor.
  • the second receptor may be a flexible sheet-form material such as paper, card, plastic film, etc., and transfer is most readily effected by means of a heated roller laminating device such as a MATCHPRINT laminator.
  • a heated roller laminating device such as a MATCHPRINT laminator.
  • the support sheet of the first receptor element is then peeled away and discarded, the peeling process being facilitated when a release layer is present between the support sheet and receptor layer.
  • BUTVAR B-76 polyvinyl butyral resin supplied by Monsanto, with free hydroxyl content of 7 mole% to 13 mole%
  • VIKING grained and anodized aluminium base printing plate base obtained by removing the photosensitive coating from VIKING printing plates supplied by Imation
  • the colorant donor sheet used in this Example comprised the following, as a layer on PET base of approximately 1 ⁇ m dry thickness in which all percentages are by weight: magenta pigment 23.2% BUTVAR B-76 48.6%
  • Samples of the donor sheet were mounted face-to-face with samples of various receptor sheets with vacuum hold down on an exposure test bed comprising a fibre-coupled laser diode (500 mW, 870 nm) focused to a 30 ⁇ m spot.
  • a halftone dot pattern was imaged on to each receptor under identical conditions of laser power and scan rate, and the quality of each of the transferred images assessed both microscopically (for dot quality) and visually (for overall appearance).
  • the following receptor sheets were tested:
  • an ink jet receptor comprising a coating on paper of starch particles (approximately 500/mm 2 , at least lO ⁇ m diameter)
  • Receptors (a) and (b) gave diffuse images with poor color saturation, whereas receptors (c) to (f) all gave sharp images with bright, saturated color.
  • Microscopic examination revealed that the dots transferred to receptors (a) and (b) had fragmented during the transfer process, with pigment scattered over a wide area, whereas the dots transferred to the other receptors were in the form of coherent films.
  • the dots on receptors (c) and (d) showed some edge distortion, but those on receptors (e) and (f) had sharp edges.
  • the image on receptor (f) suffered from "dropouts" caused by dust particles, whereas none of the other images suffered from this defect.
  • Receptor (e) illustrates the trend for improved image quality as the surface protrusions of the receptor layer become smaller and more numerous.
  • Cyan, magenta, yellow and black (CMYK) donor sheets were prepared as in Example 1 with weight percentages of components listed in the following Table in the thermofusible colorant layer coated at about lm to SWOP specifications for web off-set printing.
  • a receptor was prepared by coating the following formulation from methylethyl ketone (18 wt%) onto 100 m PET base to provide a dry coating weight of 400 mg/ft 2 (4.3 g/m 2 ):

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  • Thermal Transfer Or Thermal Recording In General (AREA)

Abstract

L'invention porte sur un procédé de production d'images demi-ton, ce procédé consistant à: (a) assembler une feuille réceptrice et une feuille donneuse de colorant, la feuille donneuse de colorant comprenant un support supportant une couche de colorant thermofusible renfermant un liant, un colorant et un agent absorbant; (b) exposer l'ensemble à un rayonnement laser balayeur d'une longueur d'onde absorbée par l'agent absorbant, le rayonnement laser étant focalisé sur un point d'une surface de A νm2 au niveau du plan de la couche de transfert de colorant et modulé conformément à des informations numériques de production d'images demi-ton, ce qui ramollit ou fait fondre les parties exposées de la couche de colorant pour les faire adhérer de préférence à la feuille réceptrice; (c) séparer la feuille réceptrice de la feuille donneuse de colorant. Ce procédé se caractérise en ce que la feuille réceptrice comprend un support recouvert d'une couche réceptrice texturée qui comporte une pluralité de parties saillantes émergeant au-dessus du plan de la surface externe de la couche réceptrice d'une distance moyenne ne dépassant pas environ 8 νm, en moyenne au moins une de ces parties saillantes apparaissant par surface de A νm2.
PCT/US1998/008095 1997-04-22 1998-04-22 Production d'images demi-ton par transfert de film par laser sur un recepteur texture WO1998047718A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU72538/98A AU7253898A (en) 1997-04-22 1998-04-22 Half-tone imaging by laser-induced film transfer to textured receptor

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US4409397P 1997-04-22 1997-04-22
US60/044,093 1997-04-22

Publications (1)

Publication Number Publication Date
WO1998047718A1 true WO1998047718A1 (fr) 1998-10-29

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1092561A2 (fr) * 1999-10-15 2001-04-18 E.I. Du Pont De Nemours And Company Procédé pour l'enregistrement par transfert thermique induit par laser
EP1145863A1 (fr) * 2000-04-14 2001-10-17 Asahi Glass Company Ltd. Procédé de préparation d' épreuve pour plaque d' impression, et moyen d' enregistrement
WO2002009948A3 (en) * 2000-07-27 2002-04-25 Imation Corp Image receptor sheet for use in laser-addressable thermal transfer recording systems
EP1228892A2 (fr) * 2001-02-02 2002-08-07 Fuji Photo Film Co., Ltd. Matériau et procédé pour la formation d'image multicolore
WO2003074278A1 (fr) * 2002-03-07 2003-09-12 Aurentum Innovationstechnologien Gmbh Procede d'impression de qualite et machine d'impression et substance d'impression a cet effet
WO2004080725A1 (fr) * 2003-03-13 2004-09-23 Koninklijke Philips Electronics N.V. Procede de marquage et objet marque
AU2005200175B2 (en) * 1999-10-15 2008-05-08 E.I. Du Pont De Nemours And Company Thermal imaging process and products using image rigidification
EP2082893A3 (fr) * 2008-01-28 2010-05-19 Fujifilm Corporation Procédé de formation d'images par transfert thermique

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US4876235A (en) * 1988-12-12 1989-10-24 Eastman Kodak Company Dye-receiving element containing spacer beads in a laser-induced thermal dye transfer
US5017547A (en) * 1990-06-26 1991-05-21 Eastman Kodak Company Use of vacuum for improved density in laser-induced thermal dye transfer
EP0544283A1 (fr) * 1991-11-26 1993-06-02 Eastman Kodak Company Surface texturée entre donneur et récepteur pour transfert thermique de colorant induit par laser
EP0675003A1 (fr) * 1994-03-29 1995-10-04 Minnesota Mining And Manufacturing Company Formation d'images par transfert thermique
US5518861A (en) * 1994-04-26 1996-05-21 E. I. Du Pont De Nemours And Company Element and process for laser-induced ablative transfer

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US4876235A (en) * 1988-12-12 1989-10-24 Eastman Kodak Company Dye-receiving element containing spacer beads in a laser-induced thermal dye transfer
US5017547A (en) * 1990-06-26 1991-05-21 Eastman Kodak Company Use of vacuum for improved density in laser-induced thermal dye transfer
EP0544283A1 (fr) * 1991-11-26 1993-06-02 Eastman Kodak Company Surface texturée entre donneur et récepteur pour transfert thermique de colorant induit par laser
EP0675003A1 (fr) * 1994-03-29 1995-10-04 Minnesota Mining And Manufacturing Company Formation d'images par transfert thermique
US5518861A (en) * 1994-04-26 1996-05-21 E. I. Du Pont De Nemours And Company Element and process for laser-induced ablative transfer

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU780111B2 (en) * 1999-10-15 2005-03-03 E.I. Du Pont De Nemours And Company Thermal imaging process and products using image rigidification
AU2005200175B2 (en) * 1999-10-15 2008-05-08 E.I. Du Pont De Nemours And Company Thermal imaging process and products using image rigidification
EP1092561A3 (fr) * 1999-10-15 2003-05-21 E.I. Du Pont De Nemours And Company Procédé pour l'enregistrement par transfert thermique induit par laser
EP1634720A3 (fr) * 1999-10-15 2007-01-17 E.I.Du pont de nemours and company Procédé pour l'enregistrement par transfert thermique induit par laser
EP1647413A1 (fr) * 1999-10-15 2006-04-19 E.I.Du pont de nemours and company Procédé pour l'enregistrement par transfert thermique induit par laser
EP1092561A2 (fr) * 1999-10-15 2001-04-18 E.I. Du Pont De Nemours And Company Procédé pour l'enregistrement par transfert thermique induit par laser
EP1145863A1 (fr) * 2000-04-14 2001-10-17 Asahi Glass Company Ltd. Procédé de préparation d' épreuve pour plaque d' impression, et moyen d' enregistrement
US7073443B2 (en) 2000-04-14 2006-07-11 Asahi Glass Company, Limited Method for preparing proof for plate printing, and recording medium
WO2002009948A3 (en) * 2000-07-27 2002-04-25 Imation Corp Image receptor sheet for use in laser-addressable thermal transfer recording systems
US6946425B2 (en) 2001-02-02 2005-09-20 Fuji Photo Film Co., Ltd. Multicolor image forming material and method for forming multicolor image
EP1640174A2 (fr) * 2001-02-02 2006-03-29 Fuji Photo Film Co., Ltd. Matériau et procédé pour la formation d'image multicolore
EP1640174A3 (fr) * 2001-02-02 2006-04-05 Fuji Photo Film Co., Ltd. Matériau et procédé pour la formation d'image multicolore
US6758932B2 (en) 2001-02-02 2004-07-06 Fuji Photo Film Co., Ltd. Multicolor image forming material and method for forming multicolor image
EP1228892A3 (fr) * 2001-02-02 2003-07-02 Fuji Photo Film Co., Ltd. Matériau et procédé pour la formation d'image multicolore
EP1228892A2 (fr) * 2001-02-02 2002-08-07 Fuji Photo Film Co., Ltd. Matériau et procédé pour la formation d'image multicolore
WO2003074278A1 (fr) * 2002-03-07 2003-09-12 Aurentum Innovationstechnologien Gmbh Procede d'impression de qualite et machine d'impression et substance d'impression a cet effet
US7154522B2 (en) 2002-03-07 2006-12-26 Aurentum Innovationstechnologien Gmbh Quality printing method, printing machine, and corresponding printing substance
WO2004080725A1 (fr) * 2003-03-13 2004-09-23 Koninklijke Philips Electronics N.V. Procede de marquage et objet marque
EP2082893A3 (fr) * 2008-01-28 2010-05-19 Fujifilm Corporation Procédé de formation d'images par transfert thermique
US7760219B2 (en) 2008-01-28 2010-07-20 Fujifilm Corporation Method of forming image by thermal transfer

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