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
  • B41M5/24—Ablative recording, e.g. by burning marks; Spark recording
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M2205/00—Printing methods or features related to printing methods; Location or type of the layers
  • B41M2205/30—Thermal donors, e.g. thermal ribbons
• • 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
  • B41M5/38207—Contact thermal transfer or sublimation processes characterised by aspects not provided for in groups B41M5/385 - B41M5/395
  • B41M5/38214—Structural details, e.g. multilayer systems
• • 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
  • B41M5/385—Contact thermal transfer or sublimation processes characterised by the transferable dyes or pigments
  • B41M5/3854—Dyes containing one or more acyclic carbon-to-carbon double bonds, e.g., di- or tri-cyanovinyl, methine
• • 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
  • B41M5/385—Contact thermal transfer or sublimation processes characterised by the transferable dyes or pigments
  • B41M5/388—Azo dyes
• • 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
  • B41M5/385—Contact thermal transfer or sublimation processes characterised by the transferable dyes or pigments
  • B41M5/39—Dyes containing one or more carbon-to-nitrogen double bonds, e.g. azomethine
• • 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
  • B41M5/41—Base layers supports or substrates
• • 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
  • B41M5/426—Intermediate, backcoat, or covering layers characterised by inorganic compounds, e.g. metals, metal salts, metal complexes
• • 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
  • B41M5/44—Intermediate, backcoat, or covering layers characterised by the macromolecular compounds

Definitions

• This invention relates to a laser recording element, and more particularly to a single-sheet laser recording element wherein the support is a microvoided composite film.
• the donor sheet includes a material which strongly absorbs at the wavelength of the laser.
• this absorbing material converts light energy to thermal energy and transfers the heat to the dye in the immediate vicinity, thereby heating the dye to its vaporization temperature for transfer to a receiver.
• the absorbing material may be present in a layer beneath the dye and/or it may be admixed with the dye.
• the laser beam is modulated by electronic signals which are representative of the shape and color of the original image, so that each dye is heated to cause volatilization only in those areas in which its presence is required on the receiver to reconstruct the color of the original object. Further details of this process are found in GB 2,083,726A.
• U.S. Patent No. 5,330,876 relates to a dye ablative recording element as described above.
• the element comprises a support having thereon a dye layer containing an image dye, IR-absorbing dye and binder.
• the element is imagewise-exposed by a laser and portions of the dye layer are ablated away to produce a dye image.
• the support for this element is the conventional supports used in this field.
• a laser recording element comprising a base having thereon a dye layer comprising an image dye dispersed in a polymeric binder, the dye layer having an infrared-absorbing material associated therewith, the base comprising a composite film laminated to at least one side of a support, the dye layer being on the composite film side of the base, and the composite film comprising a microvoided thermoplastic core layer and at least one substantially void-free thermoplastic surface layer.
• Another embodiment of the invention relates to a process of forming a dye image comprising imagewise-heating, by means of a laser, the recording element described above, the laser exposure taking place through the dye side of the element and causing dye to be removed imagewise to obtain the dye image in the recording element.
• dye is removed imagewise by means of an air stream, vacuum and filter system.
• any polymeric material may be used as the binder in the recording element employed in the invention.
• cellulosic derivatives e.g., cellulose nitrate, cellulose acetate hydrogen phthalate, cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose triacetate, a hydroxypropyl cellulose ether, an ethyl cellulose ether, etc., polycarbonates; polyurethanes; polyesters; poly(vinyl acetate); polystyrene; poly(styrene-co-acrylonitrile); a polysulfone; a poly(phenylene oxide); a poly(ethylene oxide); a poly(vinyl alcohol-co-acetal) such as poly(vinyl acetal), poly(vinyl alcohol-co-butyral) or poly(vinyl benzal); or mixtures or copolymers thereof.
• the binder may be used at a coverage of from about 0.1
• the polymeric binder used in the recording element employed in the process of the invention has a polystyrene equivalent molecular weight of at least 100,000 as measured by size exclusion chromatography, as described in U.S. Patent 5,330,876.
• the laser radiation is then absorbed into the dye layer and converted to heat by a molecular process known as internal conversion.
• a useful dye layer will depend not only on the hue, transferability and intensity of the image dyes, but also on the ability of the dye layer to absorb the radiation and convert it to heat.
• the infrared-absorbing dye may be contained in the dye layer itself or in a separate layer associated therewith, i.e., above or below the dye layer.
• the laser exposure in the process of the invention takes place through the dye side of the recording element, which enables this process to be a single-sheet process, i.e., a separate receiving element is not required.
• the dye layer of the laser recording element of the invention may be coated on the support or printed thereon by a printing technique such as a gravure process or a hopper coater.
• the support may include cellulose paper, a polymeric film or a synthetic paper.
• microvoided packaging films can be laminated to one side of most supports and still show excellent curl performance. Curl performance can be controlled by the beam strength of the support. As the thickness of a support decreases, so does the beam strength. These films can be laminated on one side of supports of fairly low thickness/beam strength and still exhibit only minimal curl.
• Microvoided composite packaging films are conveniently manufactured by coextrusion of the core and surface layers, followed by biaxial orientation, whereby voids are formed around void-initiating material contained in the core layer.
• Such composite films are disclosed in, for example, U.S. Patent 5,244,861.
• the core of the composite film should be from 15 to 95% of the total thickness of the film, preferably from 30 to 85% of the total thickness.
• the nonvoided skin(s) should thus be from 5 to 85% of the film, preferably from 15 to 70% of the thickness.
• the density (specific gravity) of the composite film should be between 0.2 and 1.0 g/cm 3 , preferably between 0.3 and 0.7 g/cm 3 . As the core thickness becomes less than 30% or as the specific gravity is increased above 0.7 g/cm 3 , the composite film starts to lose useful compressibility and thermal insulating properties.
• the composite film becomes less manufacturable due to a drop in tensile strength and it becomes more susceptible to physical damage.
• the total thickness of the composite film can range from 20 to 150 ⁇ m, preferably from 30 to 70 ⁇ m. Below 30 ⁇ m, the microvoided films may not be thick enough to minimize any inherent non-planarity in the support and would be more difficult to manufacture. At thicknesses higher than 70 ⁇ m, little improvement in either print uniformity or thermal efficiency is seen; and so there is not much justification for the further increase in cost for extra materials.
• Suitable polyolefins include polypropylene, polyethylene, polymethylpentene, and mixtures thereof.
• Polyolefin copolymers, including copolymers of ethylene and propylene are also useful.
• the composite film can be made with skin(s) of the same polymeric material as the core matrix, or it can be made with skin(s) of polymeric composition different from that of the core matrix.
• an auxiliary layer can be used to promote adhesion of the skin layer to the core.
• Addenda may be added to the core matrix to improve the whiteness of these films. This would include any process which is known in the art including adding a white pigment, such as titanium dioxide, barium sulfate, clay, or calcium carbonate. This would also include adding optical brighteners or fluorescing agents which absorb energy in the UV region and emit light largely in the blue region, or other additives which would improve the physical properties of the film or the manufacturability of the film.
• a white pigment such as titanium dioxide, barium sulfate, clay, or calcium carbonate.
• optical brighteners or fluorescing agents which absorb energy in the UV region and emit light largely in the blue region, or other additives which would improve the physical properties of the film or the manufacturability of the film.
• Coextrusion, quenching, orienting, and heat setting of these composite films may be effected by any process which is known in the art for producing oriented film, such as by a flat film process or by a bubble or tubular process.
• the flat film process involves extruding the blend through a slit die and rapidly quenching the extruded web upon a chilled casting drum so that the core matrix polymer component of the film and the skin components(s) are quenched below their glass transition temperatures (Tg).
• Tg glass transition temperatures
• the quenched film is then biaxially oriented by stretching in mutually perpendicular directions at a temperature above the glass transition temperature of the matrix polymers and the skin polymers.
• the film may be stretched in one direction and then in a second direction or may be simultaneously stretched in both directions. After the film has been stretched it is heat set by heating to a temperature sufficient to crystallize the polymers while restraining the film to some degree against retraction in both directions of stretching.
• the support to which the microvoided composite films are laminated for the base of the recording element of the invention may be a polymeric, synthetic paper, or cellulose fiber paper support, or laminates thereof.
• Preferred cellulose fiber paper supports include those disclosed in U.S. Patent 5,250,496.
• a cellulose fiber paper support it is preferable to extrusion laminate the microvoided composite films using a polyolefin resin.
• the backside of the paper support i.e., the side opposite to the microvoided composite film
• may also be extrusion coated with a polyolefin resin layer e.g., from about 10 to 75 g/m 2
• a backing layer such as those disclosed in U.S. Patents 5,011,814 and 5,096,875.
• relatively thick paper supports e.g., at least 120 ⁇ m thick, preferably from 120 to 250 ⁇ m thick
• relatively thin microvoided composite packaging films e.g., less than 50 ⁇ m thick, preferably from 20 to 50 ⁇ m thick, more preferably from 30 to 50 ⁇ m thick.
• relatively thin paper or polymeric supports e.g., less than 80 ⁇ m, preferably from 25 to 80 ⁇ m thick
• relatively thin microvoided composite packaging films e.g., less than 50 ⁇ m thick, preferably from 20 to 50 ⁇ m thick, more preferably from 30 to 50 ⁇ m thick.
• Packaging films may be laminated in a variety of way (by extrusion, pressure, or other means) to a paper support.
• they were extrusion-laminated as described below with pigmented polyolefin onto a paper stock support.
• the pigmented polyolefin was polyethylene (12 g/m 2 ) containing anatase (titanium dioxide) (12.5% by weight) and a benzoxazole optical brightener (0.05% by weight).
• the paper stock support was 137 ⁇ m thick and made form a 1:1 blend of Pontiac Maple 51 (a bleached maple hardwood kraft of 0.5 ⁇ m length weighted average fiber length), available from Consolidated Pontiac, Inc., and Alpha Hardwood Sulfite (a bleached red-alder hardwood sulfite of 0.69 ⁇ m average fiber length), available form Weyerhauser Paper Co.
• the backside of the paper stock support was coated with high-density polyethylene (30 g/m 2 ).
• a non-microvoided support was prepared by extrusion-coating a pigmented polyolefin unto a paper stock support.
• the pigmented polyolefin was polyethylene (12 g/m 2 ) containing anatase (titanium dioxide) (12.5% by weight) and a benzoxazole optical brightener (0.05% by weight).
• the paper stock support was the same as described above.
• the backside of the paper stock support was coated with high-density polyethylene (30 g/m 2 ).
• the elements were exposed using Spectra Diode Labs Lasers Model SDL-2432, with a maximum power of 600 mW per laser beam, at 830 nm, 1000 rev/min and a spot size of approximately 12 ⁇ m x 25 ⁇ m using a lathe type printer with a drum circumference of 53 cm.
• the diode laser beams were scanned across the surface of the element to achieve 945 lines per cm, or 2400 lines per in.
• An air stream was blown over the donor surface along with a vacuum and a filter system to remove the ablated material.
• a step tablet image was printed by reducing the laser intensity linearly in successive patches from the maximum to 0.
• Reflection Status A red densities were measured using an X-Rite Model 310 reflection densitometer.

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• Thermal Transfer Or Thermal Recording In General (AREA)

Applications Claiming Priority (4)

Publications (3)

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• 1996
  • 1996-08-15 DE DE69604636T patent/DE69604636T2/de not_active Expired - Fee Related
  • 1996-08-15 EP EP96202291A patent/EP0761468B1/fr not_active Expired - Lifetime
  • 1996-08-29 JP JP08228710A patent/JP3097903B2/ja not_active Expired - Fee Related

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