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
  • B41M5/267—Marking of plastic artifacts, e.g. with laser
• • 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
  • 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

Definitions

• TITLE PROCESS FOR MAKING A MARKING OF DIFFERENT IRREVERSIBLE COLORS FROM THE SAME COMPOSITION
• the invention relates to a method of producing a marking of different colors from the same composition.
• markings are widely used whether from inks, paints, varnishes, or directly in the material in the case of plastics in particular to make patterns intended to fight against fraud or in a decorative purpose.
• a known process consists in degrading the material conferring a base color, by temperature for example so that the organic material turns brown or even blackens.
• the black associated with this browning is nothing other than a carbonization of said material and the marking produced appears in black compared to the base color.
• the only color of the marking is therefore black without any possibility of producing different colors and if this were the case, it could only be shades of gray, difficult to control.
• Another solution for carrying out a color marking according to a given surface graphics consists in providing several layers of different colors superimposed on the same support and in removing the layers necessary to reveal the desired color corresponding to a given layer according to a defined surface graphics.
• green can be eliminated in order to reveal the red part of the surface graphic and / or the green layer and the red layer can be eliminated to reveal the blue part of the surface graphic.
• the difficulty consists in being able to remove very thin layers and the work consists of an ablation so that traces of the ablation may remain, the definition remains limited and the duration of such a service is long with an extremely limited quality. .
• thermochromic pigments absorb infrared radiation, in a well-known manner.
• thermochromic pigments when subjected to infrared radiation, changes color. This is very interesting for determining at what temperature a product is at a given moment, but the material returns to its initial color as soon as the submission to infrared radiation ceases. Such a process is reversible and therefore does not find application in the field of security.
• a patent EP 2722367 is known from the prior art which describes a composition of dyes, soluble in methylene chloride and capable of changing color depending on the type of infrared energy emitted, with a maximum absorption at- above llOOnm.
• This formulation makes it possible to design different compositions capable of generating a color with more or less density.
• This modular formulation increases the range of colors available.
• three compositions from the same base are superimposed with a complex process of implementation and all the superimposed layers are treated by three lasers at a given power and at a given frequency to reveal a color. Indeed, only the composition of the layer concerned reacts with the associated laser parameters.
• PCT / EP2016 / 061069 similarly describes a superposition of layers capable of generating a given color under activation by a laser of a given wavelength.
• This document does not reiterate this process but wishes to propose a more ecological composition and wishes to use a solvent that is more respectful of the environment, that is to say water, or even 90% water.
• Document US 4861620 describes a method of changing the colors of the pigments present on the surface of a product by increasing the temperature of the product by means of a laser. This phenomenon is linked to the loss of water molecules contained in thermochromium pigments.
• the thermochromium pigments used in this method require a high temperature to change color.
• a high temperature causes the deterioration of the product itself.
• Document DE 10054803 relates for its part to a process for lightening a plastic surface comprising several layers of materials each comprising a pigment capable of lightening depending on the temperature to which each pigment is exposed. This configuration is very limiting and requires the use of different pigments on several layers of materials.
• the present invention relates to a color marking in a composition attached to a matrix, that is to say a functionalized coating of the ink, paint or varnish type, to be attached to a support, or to be integrated into the support, by example a functionalized plastic material, excluding any ablation of material constituting said matrix.
• Such color markings are much more complex to reproduce by fraudsters, are directly visible to the owner, can be recognized without having to you might as well enter indications in natural language.
• a cardholder's card is recognizable by the colors used, the graphics of the marking, the combination of the colors of the marking which confer a unique identification.
• the aim is also to allow high-speed marking work, therefore inexpensive, tamper-proof to guarantee safety and impossible to reproduce without knowledge of the marking parameters, of the composition used and of the irreversible color change pigments induced by a thermo- and / or photo-assisted process.
• the solution according to the present invention consists in using a matrix integrating at least one irreversible photo-induced and / or thermochromium pigment.
• This at least one photo-induced and / or thermochromium pigment requires an energy intensity to go from a first initial fundamental state to an excited state and then to come to a second stable ground state, by generating a given color. Irreversibility results from the fact that it would take too much energy to bring it back to its first ground state, with its base color. Indeed, the necessary energy level would induce degradation of the matrix which necessarily has limits of resistance to degradation.
• the solution according to the present invention is aimed at a process consisting in integrating at least one irreversible photo-induced and / or thermochromium compound in a matrix, in subjecting it to an activation energy sufficient to cause it to change state, said energy. to be less than the degradation energy of said matrix.
• the energy input is produced from a pulsed laser beam and more particularly a fiber laser. More particularly still, the working wavelength of said fiber laser is 1.06 ⁇ m.
• the power of the fiber laser is 20W to adapt the intensity of the energy emitted according to the desired marking. The power of the laser is lower, for a given frequency, than the degradation energy of the matrix.
• thermochromium pigment has the property of changing colors depending on the temperature to which it is exposed.
• a photo-induced pigment has the property of changing colors depending on the light to which it is exposed.
• the matrix containing the pigment is not exposed to too high a temperature which could degrade it.
• the matrix is thus subjected to sufficient activation energy to cause the pigment to change state by electronic excitation, but this activation energy remains lower than the degradation energy of the matrix.
• the pigments developed by the company Olikrom have the photo-induced and / or thermochromic qualities necessary for the present process.
• FIG. 1 represents a typical graph for a base color, dark blue, this by varying the power on the ordinate and the frequency on the abscissa.
• FIG. 2 represents a typical graph for a base color, brown, this by varying the power on the ordinate and the frequency on the abscissa.
• FIG. B represents a typical graph for a basic color, turquoise blue, this by varying the power on the ordinate and the frequency on the abscissa.
• FIG. 4 represents a typical graph for a basic color, black, this by varying the power on the ordinate and the frequency on the abscissa.
• the marking method according to the present invention is illustrated with regard to a control which is a support, for example polycarbonate, or having received a layer of the matrix, for example a polyurethane, comprising at least one photo-induced pigment and / or thermochromium, either having been functionalized in the mass with said composition, making it possible to show the variations in power and in frequency.
• the exemplifying choice implements a support in the form of a credit card on which a checkerboard with the frequency on the x-axis and the power on the y-axis.
• the material of the support has a known point of degradation of the material, this point being variable depending on the nature of the materials.
• marking means any inscription, any geometric surface or wireframe shape, produced on the surface of said support or in the support when the material has been functionalized in the mass.
• the references 1 to 4 show in the checkerboard, the measurement points for each color tested and the markings consist of square pixels of a few tenths of a millimeter each.
• integrated into a support is understood to mean:
• thermochromium pigment either the introduction of at least one irreversible photo-induced and / or thermochromium pigment into the support during the manufacture of said support
• At least one photo-induced and / or thermochromic pigment integrated in a matrix attached in a layer on the surface of said support.
• the color marking process comprises the succession of the following steps:
• the matrix comprises a single pigment to obtain a marking of different colors and a single layer of ink.
• the method consists in emitting an energy beam with a pulsed laser, in particular a fiber laser, even more a fiber laser emitting at the wavelength of 1.06 ⁇ m.
• the nominal power is 20W.
• the frequency f expressed in kilohertz KHz, increases by 20kHz for each next pixel of the checkerboard, this for the same percentage of the nominal power.
• the power is expressed in Watt and goes from 0 to 100%.
• the maximum power emitted remains below the degradation power of the matrix.
• the color obtained is defined according to the reference L, a, b, de the CIELAB color space. This repository consists of defining:
• - b represents the value on a blue / yellow axis.
• the tests are carried out on a polycarbonate support covered with a layer of the matrix according to the present invention, arranged in the form of pixels, in checkers.
• the at least one pigment could have been incorporated into the polycarbonate material directly.
• the matrix incorporates a single irreversible photo-induced and / or thermochromium pigment, the basic color of which, in the visible, is dark blue defined in the table by the parameters L, a, b.
• L, a, b the basic color of which, in the visible, is dark blue defined in the table by the parameters L, a, b.
• the second test is carried out on a brown background from a matrix incorporating a single photo-induced pigment and / or irreversible thermochromium of brown color with an L, a, b colorimetry indicated in Table 2 below.
• Brown gives variations in greens and yellows. Greens appear when the intensity increases, it is the color change from brown to green and the frequency limits the color change from yellow to green. It can be seen that brown is quickly transformed into yellow and green colors. Yellow quickly becomes predominant as the frequency increases.
• the third test is carried out on a turquoise blue background from a matrix incorporating a photo-induced and / or irreversible thermochromium pigment, turquoise blue with the parameters L, a, b defined in Table 3 below. Turquoise blue is therefore a lighter blue. The impact is important because the colors that appear during variations in power and frequency change from beige to burgundy through light oranges.
• the fourth test is carried out on a black background with color variations from black to beige, orange, purple and pink.
• the parameters L, a, b are defined in Table 4 below. [00BB] [Tables 4]
• the tests were carried out with a single photo-induced pigment and / or thermochromium.
• the method provides for the introduction of at least one pigment and it is possible to combine two or more photo-induced and / or thermochromic pigments to adjust and obtain an infinity of colors.

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• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Thermal Transfer Or Thermal Recording In General (AREA)
• Heat Sensitive Colour Forming Recording (AREA)

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Citations (4)

Family Cites Families (5)

• 2020
  • 2020-01-28 FR FR2000830A patent/FR3106527B1/fr active Active
• 2021
  • 2021-01-28 EP EP21705884.1A patent/EP4096930A1/de active Pending
  • 2021-01-28 WO PCT/EP2021/051999 patent/WO2021152018A1/fr not_active Ceased

Patent Citations (4)

Non-Patent Citations (1)

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