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
  • 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
  • B41M5/382—Contact thermal transfer or sublimation processes
  • B41M5/392—Additives, other than colour forming substances, dyes or pigments, e.g. sensitisers, transfer promoting agents

Definitions

• the invention relates to a thermal ribbon, in particular thermocarbon ribbon, with a customary carrier and a layer of a melting ink formed on one side of the carrier, which contains pigments and optionally dyes and other additives.
• Thermal ribbons have long been known, they have a melting color on a film-like carrier, for example made of paper, a plastic or the like, in particular in the form of a plastic and / or wax-bound colorant or carbon black layer.
• the melting ink is melted by means of a thermal print head and transferred to a recording paper or a printing paper.
• Thermal printers or thermal print heads that can be used for this process are e.g. B. from DE-ASen 2 062 494 and 2 406 613 and DE-OS 3 224 445 known.
• z. B. proceed as follows:
• a letter consisting of heated dots and to be printed on a paper sheet is formed on the thermal print head of the printer.
• the thermal print head presses the thermal ribbon onto the paper to be written on.
• the heated letter of the thermal print head at a temperature of about 400 ° C leads to the melting ink being melted at the heated point and being transferred to the paper sheet in contact with it.
• the used part of the thermal ribbon is fed to a spool.
• the thermal ribbon can have different melting colors next to each other. With the combination of the basic colors blue, yellow and red, colored print images can be produced. Compared to the usual color photographs, there is no disadvantageous development and fixing. Thermal printers can be operated at high writing speeds (a DIN A4 sheet can be printed in about 10 seconds) and without annoying background noises.
• thermal ribbons described above there are also those in which the heat symbol is not embossed by the action of a thermal print head, but by resistance heating of a specially designed film-like carrier.
• the heat is generated by the flow of an electric current, for this purpose the melting ink and / or its support must contain electrically conductive materials.
• the melting color which represents the actual functional layer during the printing process, also contains the materials already described above.
• ETR Electro Thermal Ribbon
• a corresponding thermal transfer printing system is described, for example, in US Pat. No. 4,309,117.
• thermocarbon tapes of the type described above are unsatisfactory in terms of opacity during the writing process.
• the invention was therefore based on the object of proposing a thermal ink ribbon which is distinguished in that it leads to particularly optically dense prints during the printing process.
• the melting ink contains at least one paraffin with a solidification temperature of about 50 to 110 ° C. and at least one ethylene-vinyl acetate wax which is capable of forming a eutectic with the paraffin.
• An essential component of the melting color of the thermocarbon tape according to the invention is therefore a paraffin that melts within the temperature range of approximately 50 to 110 ° C., preferably between approximately 60 to 95 ° C. It is a solid mixture of cleaned. saturated, aliphatic hydrocarbons, which are colorless, odorless and tasteless, dissolve easily in ether and chloroform and do not dissolve in water and 90% alcohol. Micro waxes ceresin, petrolat and Fischer-Tropsch waxes can be given as specific examples of pharaffinic materials which come under the term "paraffin" chosen here.
• Another essential component of the melting ink is another wax which, with the paraffin wax of the type described above, is capable of forming a eutectic when the homogeneous melt cools. This can result in a pure eutectic or a mixture of the eutectic with one of the two pure components. Surprisingly, it has been shown that, taking the above requirement into account, the task is solved to the desired extent.
• An ethylene-vinyl acetate wax is particularly suitable for forming a eutectic with the paraffin wax mentioned, in particular a melting point of about 87 to 92 ° C, a solidification point of about 83 to 97 ° C, an average molecular weight of about 6,500 to 7,000 and a vinyl acetate content of about 9 to 11%.
• a preferred ethylene-vinyl acetate wax is sold, for example, by the company BASF under the trade name "EVA 1 wax".
• the two wax materials forming the eutectic are used in a certain mixing ratio, so that ultimately about 40 to 90% by weight of the paraffinic wax and about 10 to 60% by weight of the finished solid wax mixture -% of the wax material, which forms a eutectic with this paraffin wax.
• the melting ink which essentially consists of the two wax materials described above
• various conventional additives can be incorporated into the melting ink.
• ester waxes and / or modified hydrocarbon resins which promote the flow processes in the thermal printing process, in particular lower the viscosity.
• thermocarbon tape according to the invention pigments are contained in the melting ink. Dyes may optionally also be present. The usual definition that differentiates between pigments and dyes should be considered. Both terms are encompassed by the more general term "colorant”.
• colorant The particular effects which can be achieved with the invention, in particular the improved color density of the printed symbol, seem to be due to the fact that the pigments, in particular carbon black, when the melt is applied from the constituents of the subsequent melting ink when the solid mixture is formed, with the formation of a eutectic of a kind Subject to agglomeration. If the thermocarbon tape according to the invention is observed with a microscope, it can be seen that "nests" of pigments are visible in addition to more or less soot-free areas. This phenomenon is due to the special structure of the solid melting color, including a eutectic.
• a melt in a thickness of about 4 micrometers is applied in a melted form at a temperature of about 120 ° C. by means of a flexographic printing unit on a carrier made of a conventional polyester with a thickness of 4 micrometers, in which about 40 parts by weight of ethylene-vinyl acetate Wax of a melting point of about 87 to 92 ° C, a solidification point of about 83 to 97 ° C, an average molecular weight of about 6,500 to 7,000 and a vinyl acetate content of about 9 to 11 wt .-% to about 45 parts by weight of paraffin of a melting point of about 70 ° C and about 20 parts by weight of carbon black.
• a usable thermocarbon ribbon is available which, when used in thermal printers, provides prints of particularly favorable blackness.
• Example 1 was modified so that the following recipe was used to form the melting ink:

Landscapes

• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Thermal Transfer Or Thermal Recording In General (AREA)
• Impression-Transfer Materials And Handling Thereof (AREA)
• Inks, Pencil-Leads, Or Crayons (AREA)

Applications Claiming Priority (2)

Publications (3)

Family

ID=6359625

Family Applications (1)

Country Status (4)

Families Citing this family (5)

Family Cites Families (21)

• 1988
  • 1988-07-27 DE DE3825437A patent/DE3825437C1/de not_active Expired
• 1989
  • 1989-07-06 DE DE8989112329T patent/DE58904050D1/de not_active Expired - Fee Related
  • 1989-07-06 EP EP89112329A patent/EP0352519B1/de not_active Expired - Lifetime
  • 1989-07-26 US US07/553,793 patent/US5118211A/en not_active Expired - Lifetime
  • 1989-07-27 JP JP1192785A patent/JPH0775901B2/ja not_active Expired - Lifetime

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