Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
  • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
  • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
  • B42D25/30—Identification or security features, e.g. for preventing forgery
  • B42D25/36—Identification or security features, e.g. for preventing forgery comprising special materials
  • B42D25/364—Liquid crystals
• • 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
  • B41M5/28—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using thermochromic compounds or layers containing liquid crystals, microcapsules, bleachable dyes or heat- decomposable compounds, e.g. gas- liberating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
  • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
  • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
• • 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.]

Definitions

• the invention relates to a method for printing on a surface of a printing material with an application means for generating a freely programmable print image, in particular an optical effect.
• the invention further relates to a print product for generating a freely programmable print image.
• Variable print images can, for example, only be generated by computer-controlled printers, but such a variably produced print image can no longer be changed subsequently.
• the object of the invention is to provide a method and a printed product by means of which variable printed images can be produced and preferably subsequently changed.
• This object is achieved in that in a first step by any printing method, be it cliché-based or non-cliché-based, an application medium with at least one temperature-dependent optically variable component is at least partially applied to a printing material and in a second step to generate at least one print image, in particular one First optical effect of the printing material, in particular the printed surface of the printing material, is subjected at least locally to a temperature treatment.
• a printed product produced in this way thus has an application means with at least one temperature-dependent optically variable component, via which a variable print image can be produced. If the optical variability is retained at least over a longer period of time, there is also the possibility of changing the printed image, at least within this period.
• the application means comprises an optically variable component, the optical properties of which are temperature-dependent.
• a targeted e.g. Local temperature treatment of the application medium or of the printing material, in particular the surface of which is influenced, has an effect on the optical appearance and thus freely programmable print images are generated.
• Temperature treatment can e.g. by means of locally limited cooling or heating, in which case the different temperature treatments can also have different influences on the optical appearance of the print image produced thereby.
• different temperature treatments can be carried out in succession in order to keep changing the printed image. For example, first by heating and then by cooling.
• Such a temperature treatment can be generated by any possible device that allows, in particular locally limited, a change in the The temperature of the application medium. This can be done using thermal transfer strips, heated or cooled stamps, radiation sources such as (programmable) lasers etc.
• Temperature treatment can e.g. cause a specific alignment or a change in an alignment of at least one optically variable component in the application means.
• a print image can e.g. have an optically birefringent marking.
• the print image In order to avoid constant variability of the printed image, it can be provided to harden the application medium, in particular by radiation, and thus to fix the printed image. In this hardened state, the print image is independent of temperature.
• printed matter produced in this way is well suited as a decorative element, document of value, security element, authenticity element, data carrier, color transfer film, reflective film, as an identification element, in particular in security-relevant areas Areas to prevent counterfeiting, counterfeiting, access rights or the like.
• LC Liquid Crystal
• a contained solvent extracted from the applied layer with suitable means.
• the components of the LC color align more or less perfectly with one another (primary alignment process).
• a secondary alignment is then carried out at a significantly different, generally higher temperature, in that a point-by-point local temperature change of the printed layer is produced by, for example, passing a thermal transfer bar of a thermal transfer printer over the printed area.
• the desired (secondary) alignment effects are freely programmable. Depending on the temperature, either the primary alignment is canceled or a different optical effect is obtained than in the first alignment.
• Multiple secondary alignment processes can be used to produce images with a suitable choice of liquid crystals that have several different optical effects or a multicolor. These conditions are permanently fixed in a subsequent curing, for example by photopolymerization. It may be advantageous to carry out the hardening, in particular if the hardening is slow, during the heat treatment or immediately afterwards in order to make the difference between primary alignment and secondary alignment particularly visible.
• nematic or cholesteric LC systems from Merck KgaA can be used as the liquid crystal component.
• the LC systems can be applied directly or as an addition to other application media. In direct application, the LC systems can be heated and processed as a melt or can also be used with solvents.
• uncured nematic or cholesteric phases of the liquid crystals have a temperature dependency in relation to the optical properties that can be achieved and have optical effects, which is reflected, for example, in a change in the wavelengths of the reflected colors.
• the orientation of the liquid crystals i.e. influence the so-called alignment process.
• This type of liquid crystal printing inks can be polymerized by means of actinic radiation despite a proportion of solvents.
• this type of crystallinity consists of a complete arrangement of all molecules, the type of arrangement depending on the type of liquid crystals used.
• the arrangement can be linear or helical, which leads to different optical effects.
• This alignment is also known as alignment.
• the dimensions of the periodicity are in the range of the wavelength of the visible light, which causes the respective visible optical effects due to Bragg scattering or wavelength-dependent absorption or reflection or a change in the polarization property of the incident light.
• the components used consist essentially of polymerizable monomers, so that the conditions formed in the alignment process can be fixed by irradiation with UV light and the optical effects are thus permanently maintained. This fixation is carried out in a subsequent step using suitable UV lamps.
• the alignment process and thus the fact whether and to what extent a crystalline order is established depends on various parameters.
• the crystalline order is influenced by both the rate of evaporation of the organic solvent and the prevailing temperature during and after the evaporation of the solvent.
• thermal transfer printer In terms of machine technology, locally limited heating is easier to achieve than a corresponding cooling.
• a thermal transfer printer can be used here.
• the centerpiece of this technology is a thermal transfer bar, the individual areas of which can be controlled and heated using a computer.
• a resolution of, for example, up to 300 dpi is achieved in the resulting print.
• thermal transfer technology can be used to influence the alignment processes of the LC colors described above with such a resolution.
• the application of a printed image of a solvent-containing LC ink for example from Merck KgaA, to a film, the dimensions of the print and the like. a. be specified by both the cliché used and the cliché roller.
• a printed image refers to images and characters on the order of fractions of a millimeter to full areas depending on the requirement.
• the color alignment is followed by the primary alignment process in the course of evaporation of the solvent, the result of which is strongly dependent on the prevailing temperatures of the LC color itself, which in turn is closely related Are related to the temperatures of the film and the environment. Temperatures between 20 ° C. and 50 ° C., particularly preferably between 30 ° C. and 35 ° C., are preferably selected here for optimal alignment. As a result of insufficient alignment effects, other temperatures can lead to significantly different or insufficient or missing optical effects, which may, however, be desired.
• a locally defined additional change in the alignment is carried out with the aid of a thermal transfer bar guided above or below the resulting LC layer or the printing material (such as the film here).
• a thermal transfer bar guided above or below the resulting LC layer or the printing material (such as the film here).
• the resulting optical effect can be changed in a targeted manner.
• the heat treatment can also be carried out by using lasers, a temperature change being generated locally by the action of the laser radiation on the liquid crystal printing ink and / or the substrate.
• the final step is the drying process, which can be carried out under inert gas (nitrogen or argon) due to the radical-hardening components of the LC colors of Merck KGaA.
• inert gas nitrogen or argon
• all radiation sources that have a corresponding UV output power in the required wavelength range are suitable for curing. Radiation sources are preferably used here which, in addition to a high UV power, do not cause any additional heat load on the liquid crystal layer, which would lead to a change or destruction of the optical effect produced.
• several low-pressure mercury lamps are used, which in addition to the pure 254nm mercury line can also have other wavelength ranges in UV-A, UV-B and / or UV-C due to coatings on the quartz glass. Due to the favorable temperature profile of these radiation sources there is no further temperature loading of the LC colors during the drying process, so that the previously created zones of different alignments can no longer be changed.

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• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Chemical & Material Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Printing Methods (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Liquid Crystal (AREA)

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• 2003
  • 2003-06-25 DE DE10328741A patent/DE10328741A1/de not_active Withdrawn
• 2004
  • 2004-06-08 EP EP04013488A patent/EP1491359A3/fr not_active Withdrawn
  • 2004-06-23 JP JP2004185338A patent/JP2005014614A/ja active Pending
  • 2004-06-23 CA CA002472136A patent/CA2472136A1/fr not_active Abandoned
  • 2004-06-24 US US10/876,239 patent/US20050003168A1/en not_active Abandoned
  • 2004-06-24 RU RU2004119362/12A patent/RU2004119362A/ru not_active Application Discontinuation
  • 2004-06-25 CN CNB200410060051XA patent/CN100377886C/zh not_active Expired - Fee Related

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