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
  • B41M5/26—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
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S428/00—Stock material or miscellaneous articles
  • Y10S428/913—Material designed to be responsive to temperature, light, moisture
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S428/00—Stock material or miscellaneous articles
  • Y10S428/914—Transfer or decalcomania
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
  • Y10T428/24802—Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]
  • Y10T428/24893—Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.] including particulate material
  • Y10T428/24901—Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.] including particulate material including coloring matter

Definitions

• the invention relates to a method for producing a thermal ink ribbon for thermal transfer printing with a layer of a melting ink on one side of a carrier film, the melting ink containing a wax and / or a wax-like substance, a colorant, a thermoplastic binder and optionally further additives, and one then available product.
• Thermal ribbons have been known for a long time. They have a layer of a melting ink on a film-like carrier, which can be made of paper or plastic, for example, in the form of a meltable wax-bound or plastic-bound colorant or carbon black layer. In these thermal ribbons, the melting ink is melted by means of a thermal print head and transferred to a recording paper or film. This is generally referred to as a thermal transfer ribbon or TCR ribbon ("Thermal Carbon Ribbon").
• Thermal printers which emboss a heat symbol during the printing process are known, for example, from DE-ASen 2062494 and 2406613 and DE-OS 3224445. The printing process is as follows:
• the print head of a thermal printer presses the thermal ink ribbon onto the recording substrate.
• the printhead develops temperatures that can reach a maximum of around 400 ° C.
• the uncoated back of the thermal ribbon or the film-like carrier is in direct contact with the printhead or the thermal symbol formed thereon during the printing process.
• the relative speed between the thermal ink ribbon and the printing paper or film is zero.
• the melting ink in the form of the symbol to be printed is transferred from the thermal ink ribbon to the recording substrate by a melting process.
• the thermal ink ribbon is detached from the recording substrate, the molten symbol adheres to it and solidifies.
• thermal ribbons with simple film-like carriers
• heat symbol is not generated by a thermal print head but by resistance heating of a specially designed film-like carrier.
• the melting color which represents the actual "functional layer” during the printing process, also contains the materials already described above. In professional circles this is called an electro-thermal transfer process ("Electro Thermal Ribbon").
• electro-thermal transfer process Such a thermal transfer printing system is described for example in US-PS 4309117.
• thermal ribbons that advertise several times (keyword: "multiuse”). Such thermal ribbons are described for example in EP-A-0063000.
• the melting ink of the thermal ink ribbon is then a particulate material which is insoluble in the solvent of the coating liquid and does not melt below 100 ° C, and incorporates another particulate material with a melting point between 40 and 100 ° C.
• the particulate material not melting below 100 ° C should preferably be a metal oxide, a metal, an organic resin or carbon black.
• This special particulate material is intended to give the layer of the melting ink, which is a solid mixture, a heterogeneous structure which allows only a small amount of the molten colored material to be transferred to be used in each individual printing operation.
• the invention was therefore based on the object of developing the method described at the outset in such a way that it precludes the need to use environmentally harmful solvents in its preparation.
• this object is achieved in that an aqueous coating dispersion which contains the thermoplastic binder, the wax or the wax-like substance and a fat-soluble dye in finely divided form is applied in a manner known per se to the support of the thermal ribbon, the aqueous portion of the Dispersion evaporated and a thermal treatment is carried out with melting of the wax or the wax-like substance.
• the essence of the invention is therefore that an aqueous coating dispersion containing the necessary fine-particle solids is applied to the carrier film and the aqueous portion of the dispersion evaporates below the melting point of the integrated wax particles or particles of the wax-like substance and these wax particles or particles of wax-like substance can be fused by thermal treatment.
• any plastic films are suitable, which are also used as supports in conventional carbon ribbons of typewriters, but which also withstand the high temperatures mentioned during the briefly running printing process and also release the melting ink at these temperatures.
• the plastic film consists in particular of thermoplastic plastics with a higher glass transition temperature.
• polyesters used in the prior art in particular polyethylene terephthalates, polycarbonates, polyamides, polyvinyl compounds, in particular polyvinyl chloride, polyvinyl acetate, polyvinyl alcohol and polyvinyl propionate, polyethylene, polypropylene and polystyrene.
• polyethylene terephthalates and polycarbonates are preferred.
• the plastic film to be used according to the invention can also be a fabric laminated on one or both sides.
• similarly designed common composite films can be used within the scope of the invention.
• plasticizer in order to achieve improved flexibility.
• a substance that increases the thermal conductivity can also be incorporated.
• the thickness of the plastic film is determined according to the respective requirements. As a rule, however, it is relatively thin, e.g. about 3 to 6 micrometers to allow the necessary heat transfers to run optimally. This range can also be more or less far exceeded.
• wax used in connection with the invention is to be understood as far as possible.
• Such a material should generally have the following properties: not kneadable at 20 ° C, solid to brittle-hard, coarse to fine crystalline, translucent to opaque, but not glassy, meltable above 40 ° C without decomposition, but a little above the melting point relatively low-viscosity and non-stringy.
• wax-like substances should be understood to mean those materials which largely resemble the waxes with regard to the physical and chemical properties.
• the melting point of the wax or wax-like substance chosen in each case is preferably at least about 70 ° C.
• the upper limit is preferably about 90 ° C.
• the aqueous coating dispersion contains the mentioned solid particles, i.e. the thermoplastic, the wax or the wax-like substance and the fat-soluble dye and the pigment, preferably in a particle size of 0.5 to 100 micrometers and in particular of about 5 to 50 micrometers. Particularly good process products are obtained in this particle size range.
• the aqueous coating dispersion or suspension of these materials can be prepared in various ways. This can be done, for example, by suspending fine, solid particles of these materials or else by emulsifying in the melt and then cooling, preferably with stirring to maintain the finest dispersion.
• thermoplastics are hard or even brittle plastics, which soften reversibly when heat is applied and become mechanically easily deformable, in order to finally change to a viscous liquid state at high temperatures.
• thermoplastics which do not melt during the final thermal treatment, or which at most soften at most.
• thermoplastic binders include in particular polystyrene, polyvinyl acetate, polyvinyl acetal, polyvinyl chloride, polyethylene, copolymers of vinyl acetate and vinyl chlorides, polyvinyl ether, polyvinyl propionates, polyacrylates, ethylene / vinyl acetate copolymers.
• thermoplastic binders serve as a framework substance in the layer of the melting ink designed according to the invention.
• suitable known plasticizers can also be incorporated into the thermoplastic binder, e.g.
• Phthalic acid esters such as di-2-ethylhexyl phthalate, di-isononyl phthalate and di-isodecyl phthalate, aliphatic dicarboxylic acid esters, such as that of adipic acid, in particular di-2-ethylhexyl adipate and diisodecyl adipate, phosphates, such as tricresyl phosphate and triphenyl phosphate, such as fatty acid glycol, fatty acid esters -ethylbutyrate) and the like. In individual cases it can also be advantageous to incorporate stabilizers into the thermoplastic binder.
• the ratio of wax or wax-like substance to the thermoplastic binder in the aqueous coating dispersion can vary widely and is not critical for the purposes of the invention.
• the weight ratio can easily be between about 10: 1 to 1: 5.
• a weight ratio of approximately 5: 1 to 1: 1 is preferred.
• the solids content of the coating dispersion or starting dispersion originally used can likewise vary within wide limits, for example between about 20 and 80% by weight, preferably between about 30 and 60% by weight.
• fat-soluble dyes or "fat dyes” meet this requirement.
• This class includes, for example, simple azo and anthraquinone dyes, e.g. the products sold by Bayer AG under the name "Ceres dyes”.
• This also includes, in particular, the dyes Solvent Yellow 16, Solvent Yellow 29, Solvent Yellow 14, Solvent Red 1, Solvent Red 18, Solvent Red 25, Solvent Red 24, Solvent Red 19, Smoke Dye and Solvent Yellow 16 Solvent Blue 63, Solvent Blue 68, Solvent Green, Solvent Brown 1, Solvent Red 3, Solvent Green 3 and Solvent Black 3. This list is not intended to be limiting.
• pigments can also be used, such as carbon blacks, organic and / or inorganic color pigments, but also so-called fillers such as chalk, china clay, kaolin, clay, etc.
• the aqueous coating dispersion can be applied to the support in any manner, for example with a doctor knife.
• the application technology is therefore not critical. It can also be evaporated or concentrated in any way, for example by passing warm air over it.
• the temperature during evaporation or concentration of the aqueous portion of the applied aqueous coating dispersion should only be chosen so high that the wax particles or the particles of the wax-like substance are preferably not melted during the thermal treatment.
• work can also be carried out at room temperature, whereby the thermal treatment or the transfer of air would require a longer time.
• the thermal treatment of the product obtained, which is at or above the melting temperature of the wax or the wax-like substance.
• the wax or the wax-like material is fused by this thermal treatment.
• This thermal treatment can be carried out using customary measures, for example by treatment with heated rollers, exposure to warm air and thermal radiation. Through this heat treatment, the fat-soluble dye is transferred into the phase of the fused wax or the fused wax-like substance. A particularly high color yield is therefore achieved when using the thermal ink ribbon in conventional writing systems.
• the layer thickness of the melting ink should generally be between about 5 and 30 micrometers and preferably 10 to 20 micrometers (dry layer). If appropriate, an adhesion-promoting layer with a thickness of approximately 0.1 to 5 micrometers, preferably approximately 0.5 to 2 micrometers, can be arranged between the color layer and the carrier film. This preferably consists of polymeric materials of a known type.
• An aqueous dispersion was prepared using the following recipe:
• the dispersion which made up a total of 41 parts by weight, was applied by means of a doctor blade in a layer thickness of approximately 20 micrometers (based on the product which was subsequently dried) to a polyester support.
• a doctor blade By passing warm air at a temperature of 80 ° C, the aqueous portion of the applied dispersion was evaporated within a few minutes.
• a thermal treatment was then carried out with air at a temperature of about 100 ° C., the wax particles fusing together.
• the product obtained could be used directly as a thermal ribbon. It allowed an 8x multiuse.
• a thermal ribbon was produced using the following recipe:
• the 49 parts by weight of the dispersion obtained were applied to the support of a thermal ink ribbon in the manner described in Example 1 and dried. This is followed by a thermal treatment with hot air at a temperature of 100 ° C. to fuse the wax particles.
• the process product obtained also enabled an 8-fold multiuse.

Landscapes

• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Thermal Transfer Or Thermal Recording In General (AREA)
• Paints Or Removers (AREA)
• Belt Conveyors (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

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• 1987
  • 1987-08-22 DE DE19873728076 patent/DE3728076A1/de active Granted
• 1988
  • 1988-07-30 DE DE8888112415T patent/DE3864953D1/de not_active Expired - Lifetime
  • 1988-07-30 AT AT88112415T patent/ATE67448T1/de not_active IP Right Cessation
  • 1988-07-30 ES ES88112415T patent/ES2024599B3/es not_active Expired - Lifetime
  • 1988-07-30 EP EP88112415A patent/EP0304672B1/de not_active Expired - Lifetime
  • 1988-08-19 JP JP63204879A patent/JPS6469388A/ja active Pending
  • 1988-08-19 US US07/234,969 patent/US4950501A/en not_active Expired - Lifetime

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