WO2019037887A1

WO2019037887A1 - Security element for packaging and method for creating a security element with high outline definition in printed elements generated with gravure printing

Info

Publication number: WO2019037887A1
Application number: PCT/EP2018/000344
Authority: WO
Inventors: Peter Reich; Tanja Rittner; Johann Rodler
Original assignee: Constantia Hueck Folien Gmbh & Co Kg
Priority date: 2017-08-24
Filing date: 2018-07-05
Publication date: 2019-02-28
Also published as: EP3446885A1

Abstract

The invention relates to a security element for packaging, wherein the security element has a carrier substrate, characterised in that the security element has a printed security feature in the form of letters, logos, characters, numbers, symbols, motifs and similar, wherein the security feature exists as a halftone element, which has formed a defined outline at least in sections, and the security element has a fractal halftone image as a further security feature. The invention also relates to a method for the production thereof.

Description

Security element for packaging and method for producing a security element with a high marginal edge sharpness in gravure printing elements

The invention relates to a method for generating a high marginal edge sharpness in printing elements produced in gravure printing, in particular filigree elements such as letters, characters, motifs, symbols and the like, which simultaneously have an anti-counterfeiting protection. The method should be able to be used in particular for the production of packaging, for example flexible packaging films, plastic containers and container covers and the like.

Printing elements that are produced in gravure printing, especially in premium gravure printing, have to have a sharp edge (outline) for optical reasons. This is especially true for fragile printing elements, such as letters, characters, symbols, numbers, but also for subjects. In the mechanical engraving of the printing cylinder using diamond styli, however, arise when reproducing the raster resolution sawtooth edge lines. These arise from the fact that the characters or the lines and elements of a printed image are broken down into individual dots. Thus, a line is composed of many points that have a sawtooth effect on the edge.

The outline is usually introduced in its definition already in the electronic image processing. Here are elements to be provided with a grid, defined with s 95% and the outline area, ie the area with a sharp edge at 100%.

The sharp edge usually has a width of 1 to 20 pm depending on the requirements, in most cases outlines of a width of 5 to 10 pm are generated. In electronic image processing, for example, a native file produced in the usual Illustrator, ArtPro or PACKZ or similar program is converted into an EPS file and converted into an Opo file. This conversion is necessary to perform the splitting function between grid area 95%) and outline (100%) automatically.

However, this function is only applicable to linework elements (stroke elements) and not to halftone elements.

In addition, with the introduction of a new feature in electronic image processing, namely the opacity mask, the automatic creation of an outline has become impossible, as this function is not compatible with the file formats used so far. However, the opacity mask is a simplistic image-shaping tool that greatly simplifies the creation of data files, so that this feature should also be preserved in image processing.

EP 0477442 A discloses a method for producing such a sharp edge or outline in letters, wherein the outline of the letters is formed by continuous groove-shaped cells and the inner region of the letters by punctiform cells. The corresponding printing tool is produced by laser engraving. Here, the outline (the sharp edge) is introduced into the vector data.

JP 3829216 B discloses a method for producing an outline, in which a line drawing template is integrated in a bitmap image by means of a high-resolution flatbed scanner.

The outline of a line drawing image is then provided as vector data and the printing tool is produced accordingly.

Especially in packaging - in addition to the formation of fragile printing elements, such as letters, characters, symbols, numbers, but also for subjects with a sharp edge - great emphasis on the presence of tamper-proof features that allow for unambiguous identification of branded products and identify counterfeit products.

The object of the invention was to provide a security element and a method of producing it, which has sharp edges (outlines) of printing elements, in particular halftone elements, which are produced in the intaglio printing method, and optionally additionally a forgery-proof feature is produced. The method should be particularly suitable for the production of packaging, in particular flexible packaging films of plastics or metallic foils, plastic containers and container covers made of plastic films or metallic or metallized carrier substrates.

The invention therefore provides a security element for packaging, wherein the security element has a carrier substrate, characterized in that the security element is a printed security feature in the form of letters, logos, characters, numbers, symbols, motifs and the like, wherein the security feature is present as a halftone element and has at least partially a sharp edge (outline) has formed and the security element may have a fractal halftone image as another security feature.

A further subject matter of the invention is a method for producing a high marginal edge sharpness in printing elements produced in gravure printing, which are present as halftone elements, in particular of security features, characterized by the following method steps:

- Definition of a threshold for the creation of a sharp edge

- Transfer of halftone elements in bar elements

- Creation of a sharp edge when exceeding the threshold value - if applicable, creation of a feature as fractal halftone presentation for counterfeit protection.

The security element according to the invention has on a Trägerusbtrat at least one printed security feature that is generated by gravure printing or another known printing method, such as flexo, offset, screen, digital printing or the like.

For example, flexible carrier films are preferably plastic films, for example, PI, PP, MOPP, PE, PPS, PEEK, PEK, PEI, PSU, PAEK, LCP, PEN, PBT, PET, PA, PC, COC, POM, ABS, PVC , PTFE, ETFE (ethylene tetrafluoroethylene), PTFE (polytetrafluoroethylene), PVF (polyvinyl fluoride), PVDF (polyvinylidene fluoride), and EFEP (ethylene-tetrafluoroethylene-hexafluoropropylene fluoropolymer).

The carrier films preferably have a thickness of 5 to 700 μm, preferably 5 to 200 μm, particularly preferably 5 to 50 μm.

Further, as carrier substrates and pulp-free or cellulose-containing paper, thermally activated paper or composites with paper, for example composites with plastics having a basis weight of 20 - 500 g / m ² , preferably 40 - 200 g / m ² . be used.

Furthermore, woven or nonwovens, such as continuous fiber webs, staple fiber webs and the like, which may optionally be needled or calendered, may be used as the carrier substrates. Preferably such fabrics or webs of plastics, such as PP, PET, PA, PPS and the like, but it can also be woven or nonwovens made of natural, optionally treated fibers, such as viscose fibers are used. The nonwovens or fabrics used have a weight per unit area of about 20 g / m ² to 500 g / m ² . If necessary, the nonwovens or fabrics must be surface-treated. The carrier substrate is printed, for example by gravure printing with at least one security feature.

As a security feature, fragile elements in the form of letters, logos, characters, numbers, symbols, motifs and the like are preferably suitable.

In this case, for the element to be printed, which is present as a halftone element, a TIFF file is created in electronic image processing. Preferably, this has a resolution of 320 to 25600 dpi, more preferably 3200 to 12800 dpi.

For generating the sharp edge of the security feature, a threshold is then defined, from which on the halftone element a sharp edge (outline) is added. The threshold is preferably 90-95%.

A halftone element has information between 0 and 100%. In the range between 96 and 100%, no visual difference is generally discernible. For example, this range is calculated at 95%. As a result, no visual difference is recognizable, the image information contained in the range of 96-100% is compressed so to speak, whereby a sharp edge is formed.

The halftone element may be a halftone image and / or a text consisting of letters, numbers or the like.

To create a fractal halftone image, two threshold values are defined, on the one hand the upper limit for full-tone representation, and on the other hand the lower limit for white.

The threshold values are dependent on the saturation of the image content, in particular on the expression of the black channel. Furthermore, the Line width for the fractal halftone image, which is finally in the form of a line image defined.

From these parameters, a corresponding data file is created in the electronic image processing with the elements to be printed, wherein for the sharp edge or even for the representation of a fractal halftone image, the half-tone representation is converted into a stroke representation.

The fractal halftone image is preferably created from a motif or from an image. Thus, individual motifs can be processed according to customer requirements. By the chosen parameters, in particular by the individual definition of the threshold values, individual fractal halftone images can be created, which are then unique, for example, for a specific packaging. As a result, an increased security against counterfeiting is achieved, the fractal halftone image is then clearly attributable, for example, to a defined packaging for a defined product.

The choice of the threshold value also depends on the chosen motif. In general, it is advantageously placed in the area where the main modulation is to be found.

The proof of a forgery of the fractal half-image can be done in a simple manner. The fractal image is scanned in with a high resolution scanner and the pixels of that image are compared to the pixels of the original image using conventional comparison software such as Esko Graphics Viewer, Global Vision, EyeC, Gradient Pixelproof or the like.

With a consistency of usually> 80%, the authenticity of the image can be assumed; with a match of <80%, a falsification is very likely.

To produce a printing tool, a method is preferably used in which a corresponding printing cylinder with the aid of the laser or Electron beam technology according to the desired patterns, images, lines, letters, shapes and the like is illustrated.

The data file produced as described above is then exposed to a prepared printing cylinder in a corresponding exposure system. For example, with the aid of a laser or electron beam on the cylinder, for example a gravure cylinder with a core of iron pipe with a wall thickness of about 20 mm, and the following layers: 5-7 pm nickel layer, about 300 pm copper layer; existing photosensitive layer with the corresponding patterns; Shapes, lines, letters in the form of the previously defined grid are illustrated, developed and etched.

The coating of the cylinder is carried out in the usual way with a Kunststoffübertragungsrad, or by spraying, rolling, brushing, dipping, or by a curtain coating process, preferably in a layer thickness of 2-10 pm with a commercially available photosensitive composition-for example, LD 100, OHKA Kogyo Ltd or TSER-2104 E4 Fa. Think Laboratory.

However, all other known and commercially available compositions are also suitable. It is then exposed directly and / or then the cylinder is provided with an overcoat with a layer thickness of 1 - 5 pm, for example with OC-40 (OHKA Kogyo Ltd) or with an analogous similar commercially available composition.

The development takes place after the exposure in the usual manner, for example, contactless with sodium carbonate (0.5% solution), this is usually followed by a cleaning process with water, after which the cylinder is dried.

By a subsequent conventional etching process following the laser or electron beam imaging, the image, patterns, shapes and the like defined by the laser or electron beam imaging become visible the surface of the cylinder is reflected. The etching can be carried out in various ways, for example by means of a Fe (III) chloride solution or a Cu (H) chloride solution, if appropriate with the addition of HCl or H 2 SO 4. If appropriate, commercially available and known additives for flank protection can also be added to the etching solution.

The duration of the action of the etchant depends on the etchant used and is for example when using a Cu-chloride solution with the addition of an acid about 90-2400 sec.

However, it is also possible to use an electrochemical etching method.

The cylinder looks blunt and visually dark after the etching process. By a surface treatment with electrolytic or chemical shining the impression structure can be refined and a brilliant surface can be produced.

But there are also all known engraving methods applicable.

The engraving stylus is preferably a diamond stylus. Usually, symmetrically ground diamond styluses are used for producing the surface structures of an embossing tool, the styluses each being symmetrically usually at an angle of 90 °. , 105 deg. , 110 deg. , 120 deg. , 130 deg. or 140 deg. is ground. Usually, small wells are engraved into the cylinder (for example, a copper cylinder) with this engraving stylus. The engraving stylus is installed by all manufacturers of engraving machines (e.g., Ohio Engravers, Hell, Daetwyler) in an engraving head to which 2 different control units are attached. The actuator for the engraving depth is controlled by an applied DC voltage. The frequency of cell production is controlled by an applied AC voltage.

Depending on the function of the engraving machine, the engraving heads work between 2800 and 15000 Hz. That is, the engraving machine is able to beat 8000 cells at 8000 Hz into the copper cylinder. The depth of the wells is controlled by the intensity of the DC voltage. For the control of the DC voltage, a 256 stripe mode (8 bit) is preferably used. This enables the generation of different color strengths in 256 steps.

However, it is also possible to use, in particular, depending on the desired structure, the depth, spacing and shape of the individual components of the printing or even embossing effective structure, asymmetrically ground diamond stylus.

In this case, the corresponding angles of the stylus are selected depending on the above-mentioned desired properties of the desired structure.

Furthermore, the AC voltage can be deactivated or modulated. The modulation of the AC voltage can be modulated amplitude or envelope curves. This makes it possible by modulation of the DC voltage different depths, for example, in 256 different depths to introduce into the cylinder: Through this modification no longer arranged in the grid cells are generated, but the cylinder is structured. As a result, the corresponding webs can be introduced in point form.

The gravure tool can be produced on a known engraving system, for example on an Ohio or Hell engraving system.

In doing so, e.g. a TransScribe Intagliokopf or xtreme engraving head with DC voltage control used. The usually present alternating voltage supply to the engraving head can be deactivated or modulated.

Subsequently, the feed of the engraving head is calculated. By applying the DC voltage can now be the desired structure, depending on the height of the DC voltage of the engraving head in the coating of the cylinder, in or nickel, zinc, plastics, elastomers, preferably introduced into a copper coating.

Optionally, the cylinder may then be nickel plated or chrome plated in the usual way.

A surface treatment with the electrolytic or chemical shining refines the impression structure and produces a brilliant surface.

Furthermore, such a printing cylinder can also be produced in a direct laser or electron beam process. For this purpose a suitable printing surface e.g. Chromium, copper, nickel, zinc, as well as plastic, elastomers or polymer surfaces etc. are irradiated with the help of a high-energy beam and the material is removed directly. Usually, the laser beams are equipped with a beam width of 10 pm. However, it is also possible to use other beam shapes or beam sizes, for example 5 μm or else 1 μm or 800 nm (femtosechnology).

Known methods are e.g. the Scheepers, Hell Celaxy and Daetwyler DLS system. However, it is also possible at any time to use all other material-removing radiations.

These aforementioned methods, imaging, engraving and direct processing, can also be combined with each other on a printing tool.

Preferably, the halftone elements are introduced by means of engraving and the line elements by means of laser on the printing tool, but also a different combination or mixture technically and procedurally possible.

In Figure 1, the formation of a sharp edge is shown. In this case, in the area A, the formation of the sharp edge, in the area B, the subsequent screening cups of the halftone element to be printed are shown.

FIG. 2 shows a fractal halftone image which serves as an additional security element.

FIG. 2a shows the original image, which in this case represents a collection of potato chips. Figures 2b, 2c and 2d show fractal halftone images made from the original image.

Different line weights were defined.

For the image in FIG. 2b, a line thickness of 0.006 mm was defined, for the image in FIG. 2c a line thickness of 0.03 mm and for the image in FIG. 2d a line thickness of 0.04 mm.

Other line weights can be defined, for example, a line thickness of 0.060 mm.

By individual choice of the motif from which the fractal halftone image is produced and by individual determination of the thresholds to white and to full tone as the lower or upper limit, individualized security features are created.

Claims

claims:

1) security element for packaging, wherein the security element has a Trägerusbtrat, characterized in that the security element is a printed security feature in the form of letters, logos, characters, numbers, symbols, motifs and the like, wherein the security feature is present as a halftone element, the at least partially a has formed sharp edge (outline) and the security element has a fractal halftone image as another security feature.

2) Security element according to claim 1, characterized in that the halftone element is a picture element and / or a text element.

3) Security element according to one of claims 1 or 2, characterized in that the sharp edge (outline) is formed in response to the saturation of the halftone element from a threshold value of about 90- 95%.

4) A security element according to any one of claims 1 to 3, characterized in that the fractal halftone element is defined by a threshold for Volltondarstellung as the upper limit and a threshold to white as the lower limit.

5) A security element according to claim 4, characterized in that the threshold is placed in the Berich the main modulation.

6) Security element according to one of claims 3 to 5, characterized in that the fractal halftone image forms by individual definition of the thresholds a forgery-proof and uniquely assignable security feature. 7) Method for producing a high edge edge sharpness in printing elements produced in gravure printing, which are present as halftone elements, in particular of security features, characterized by the following method steps:

- Definition of a threshold for the generation of a sharp edge in dependence on the image information

- Transfer of halftone elements in line art

- Creation of a sharp edge when exceeding the threshold value

- if necessary, creation of a feature as fractal halftone representation for the protection against counterfeiting.

8) A method according to claim 7, characterized in that the threshold for the sharp edge to be formed is 90-95%.

9) Method according to one of claims 7 or 8, characterized in that the halftone element is an image or a text element.

10) Method according to one of claims 7 to 9, characterized in that the fractal halftone element is defined by a threshold for Volltondarstellung as the upper limit and a threshold to white as the lower limit.

11) A method according to claim 10, characterized in that the threshold values for the fractal halftone image are defined individually, whereby a forgery-proof security feature is generated.