Patent Application
20130134698
The invention relates to a tamper-evident adhesive security tape or label which has an optically active security feature and an optical feature.
An optically active feature for the present purposes comprehends diffractive structures, diffraction gratings, surface reliefs, holograms, kinegrams, and the like.
Adhesive security tapes or labels in the sense of the present invention fulfill two functions: on the one hand, the adhesive tape or label is intended to ensure the authenticity of a product or the integrity of a pack through the provision of an optically active security feature. Preference for this purpose is given to the use of holograms, which are well established in the product protection segment and therefore offer a high degree of acceptance, recognizability, and security. On the other hand, however, an attempt at tampering, in other words an unauthorized attempt to detach the adhesive tape or label, is to be clearly recognizable. The latter measure ensures that the user can be reasonably certain that a product protected with an adhesive tape or label of this kind is genuine and in its original packaging.
Typical holograms which are already being used today in product protection and as security features for documents of value customarily have a basic metallically lustrous appearance which gives rise, on a change in the viewing angle, to a play of rainbow colors as a result of diffraction of light at the structures of the hologram. These diffractive effects, however, are always very similar, and the metallic luster is common to all such products. Consequently there is a demand for new optically variable effects which differ from the conventional effect not only in the pattern of the hologram but also in the basic color and/or by virtue of a different luster.
Known from KR 10079525 is a hologram film and a method for its production. The construction there consists of a backing substrate, a release layer, an embossed layer (hologram layer), a partial metal layer, a masking layer, a print layer, and an adhesive layer. The print layer and the adhesive layer there have different fluorescent features. Evidence of tampering is not possible with this construction.
Known from EP-A 1 972 674 is a tamper-evident adhesive security tape or label where detachment of the label from the packaging or article that is to be secured reveals a hidden optical element.
It was an object of the invention, therefore, to provide an adhesive security tape or label which features not only an optically active security element but also optically recognizable evidence of tampering and which differs in its overall optical impression from conventional, metallically lustrous optically active structures.
The invention accordingly provides a tamper-evident adhesive security tape or label comprising a flexible backing substrate based on a flexible polymeric film, characterized in that one surface of the backing substrate bears the following applied layers:
Examples of suitable backing substrates are backing films, preferably flexible polymeric films, comprising, for example, PI, PP, MOPP, PE, PPS, PEEK, PEK, PEI, PSU, PAEK, LCP, PEN, PBT, PET, PA, PC, COC, POM, ABS, PVC, fluoropolymers, such as commercial Teflon, and the like. The backing films preferably have a thickness of 5-700 nm, more preferably 5-200 μm, very preferably 5-100 μm.
In the first step, a varnish layer a) is applied to one surface of the backing substrate, and is embossed in the same operation or in a subsequent process. The adhesion of the varnish layer a) to the backing substrate must foe sufficient for the integrated layer system not to part along this interface when the label is detached from a liner or when the adhesive tape is unwound or when the tamper evidence feature is triggered.
If the adhesion of the varnish layer a) to the backing substrate is not great enough without further measures, then it is possible for an adhesion promoter layer, which improves the adhesion of the varnish layer a) to the backing substrate, to have been applied to the backing substrate prior to varnishing with the layer a). Alternatively a backing substrate appropriately pretreated by chemical or physical means can be used,
It may, however, be entirely desirable for the integrated layer system to separate at the interface between layer a) and the backing substrate, if, for example, the label is executed as what is called a transfer label. In this embodiment of the invention, the adhesion between layer a) and the backing substrate is lower than the adhesion of the layers a) to e) to one another. Following application of the label to an article by means of the adhesive layer, the backing substrate can be removed without triggering an evidence of tampering. This evidence of tampering then comes about, for example, as a result of the so-called tape test, in which an adhesive tape or another label is adhered to the layer system remaining on the article, and removed again. In that case the tamper evidence feature is triggered and a part, of the layers according to claim 1 is removed again.
In order to lower the adhesion, the backing substrate may be provided, for example, with a release layer. Where the embossed varnish layer a) already has poor adhesion to the backing substrate, without further measures, there is no need for a release layer for application as a transfer label.
Suitable release layers include, in particular, known poorly adhering varnish compositions, based for example on methacrylate. Furthermore, it is also possible to use very thinly applied oil layers or polyamide, polyethylene, silicone or fluoropolymer wax layers as release layers. Subsequently, as described above, the varnish layer a) is applied.
On the surface remote from the backing substrate, the varnish layer a) has a surface structure, as for example a surface relief, a hologram, a diffractive structure or a diffraction grating. This structure can be produced by means of known hot-stamping or UV embossing methods, by impression from structures present on an embossing die. When a hot-stamping method is used, the varnish layer a) is a thermoplastic varnish layer; when a UV embossing method is employed, the varnish layer a) is radiation-curing. Stamping and embossing methods of these kinds are well known to the skilled person, and are disclosed in EP-A 1 310 381, the content of which is hereby incorporated in full into the present specification.
The thickness of the applied varnish layer a) may vary depending on the end product requirement and thickness of the substrate, and in general is between 0.5 and 50 μm, preferably between 2 and 10 μm, more preferably between 2 and 5 μm.
The varnish layer a) is applied, over the full area or partially, by a coating process, such as spraying, pouring, curtain coating, slot-die coating, dipping or knife coating, for example, or by a printing process, as for example gravure, flexographic, offset, screen or digital printing.
Subsequently, a semitransparent metallic layer or a high refractive index layer b) is applied to the varnish layer a).
The semitransparent metallic layer b) has an optical density of around 0.1 to 1.3, preferably of 0.1 to 0.8. An optical density of this kind ensures that the layer is still sufficiently transparent for the layers situated behind it to foe still visible to the viewer.
Examples of suitable semitransparent metallic layers include layers comprising a metal or an alloy. Suitability as metal layer is possessed by layers comprising Al, Cu, Fe, Ag, Au, Cr, Ni, Zn, Sn, Pt, Ti, Pd, and the like. Examples of suitable alloys are Cu—Al alloys, Cu—Zn alloys, and the like.
The metallic layer is applied preferably by a PVD or CVD process (sputtering, vapor deposition, gas-phase deposition).
Alternatively the layer b) may be executed as an HRI (high refractive index) layer. This HRI layer may preferably consist of a varnish layer with a high refractive index, or of a layer comprising metal compounds. Examples of suitable metal compounds are oxides or sulfides of metals, more particularly TiO2, Cr oxides, ZnS, Cu oxides, indium tin oxide, antimony tin oxide, antimony zinc oxide, FTO, ZnO, Al2O3, or silicon oxides.
Varnish layers with a high refractive index are applied preferably by known printing or coating processes (see above); HRI layers comprising metal compounds are applied preferably by a PVD or CVD process (sputtering, vapor deposition).
Subsequently a release varnish layer c) is applied partially, in the form, for example, of letters, signs, symbols, lines, guilloches, numbers or writing.
Suitable release varnish comprises preferably known, poorly adhering varnish compositions, based for example on cycloolefin copolymers, nitrocellulose, acrylates, polyvinyl chloride, ethylene-acrylate copolymers or styrene-acrylates in a suitable solvent. To adjust the adhesion it is preferred in this case to add chlorinated polyolefins. The fraction of the chlorinated polyolefins in the composition may be 0 to 130 wt. % in relation to the base polymer.
An alternative possibility is to use any desired varnish systems, their adhesion reduced by an additive, as for example a polyacrylate copolymer (available, for example, under the brand name BYK-394® from BYK-Chemie GmbH).
It is also possible, furthermore, to use very thinly applied polyamide, polyethylene, or fluoropolymer wax layers, or silicone coatings.
The release varnish layer may optionally be provided with security pigments such as fluorescent pigments and the like.
The adhesion of the release varnish layer c) is set so that when the tamper evidence feature is triggered, the release varnish coating c) parts either from the layer b) or the layer d), but the rest of the film construction remains intact, in its structure at these locations. In any case, the adhesion of the release varnish layer c) to the layer b) is lower than the adhesion of the semi transparent or HRI layer b) to the stamping/embossing varnish layer a).
The release varnish layer c) is applied partially by means of a printing process, such as by gravure, flexographic, offset, screen, or digital printing, for example.
Applied partially or over the full area to this release varnish layer are one or more varnish layers d) having optical properties.
The optical properties of the layer d), more particularly the color, can be brought about by means of dyes and/or pigments. Pigments which can be used include all known pigments, examples being inorganic-based pigments, such as titanium dioxide, zinc sulfide, kaolin, indium tin oxide, antimony tin oxide, fluorine tin oxide, aluminum, chromium oxides and silicon oxides, or organic-based pigments, such as phthalocyanine blue, isoindolidine yellow, dioxazine violet, and the like, and also colored and/or encapsulated pigments in chemically, physically or reactively drying binder systems. Suitable dyes include, for example, 1,1- or 1,2-chromium-cobalt complexes.
Additionally it is possible for effect and/or security dyes and/or pigments to be employed, examples being luminescent dyes and pigments, which fluoresce or phosphoresce in the visible, UV or IR range; effect pigments such as liquid crystals, mother-of-pearl, bronzes and/or multilayer color-change pigments and thermochromic inks and pigments. They can be used individually or in all possible combinations. Also conceivable are combinations of visible with invisible color pigments and effect pigments and/or security pigments.
This layer or these layers d) may also, however, have a defined color gradation, or else may be executed in multicolor printing with partial or full overlap above or alongside one another and in partial or full-area form.
The colored layer or layers d) are applied by any desired process, but preferably by a printing process.
The thickness of the color layers d) is a function of the desired hiding power of the color, in conjunction with the printing process used.
Subsequently a self-adhesive coating e) is applied. With the aid of the self-adhesive coating, the adhesive security tape or label is adhered to the article or pack that is to be secured.
As a result of the different partial adhesion relationships in the label, the varnish layer d) suffers destructive tearing on any attempt to remove the adhesive tape or label from the article to be secured. One part of the varnish layer d) remains on the article to be secured; the second part of the varnish layer d) is removed with the backing substrate from the article. The two parts have a complementary behavior relative to one another—that is, either positive structures are visible on the removed backing substrate and negative structures on the article, or vice-versa.
The following boundary conditions must be observed in every case in order to ensure a reliable operation:
In view of the particular circumstances when the tamper-evidence feature is triggered, these circumstances being unable to be foreseen by the label manufacturer, it is possible for different combinations of the above boundary conditions to occur in a single label. The design of the label, however, is initially selected such that in the two relevant regions (with and without release varnish c)), one of the two above cases preferentially occurs.
Optionally, the surface of the backing substrate situated opposite to the construction may additionally bear an applied print primer, which enables or facilitates subsequent printing of a label or adhesive tape.
This printing may consist, for example, of customer-specific or product-specific individual data, or else of any desired patterns, signs, symbols, and the like.
In the case of use as an adhesive tape, the second surface of the backing substrate may optionally bear an applied release varnish layer, in order to allow the tape to be wound up; in this case, the adhesion of the self-adhesive coating e) to this second release varnish layer is poorer than the adhesion to the integrated system formed by the layers a) to e).
Embodiments in accordance with the invention are shown in
In these figures
1 denotes the backing substrate
2 denotes a varnish layer having an optically active structure (a hologram, for example)
3 denotes a semitransparent metal layer or an HRI layer
4 denotes the partial release varnish layer
5 denotes the layer having optical properties
6 denotes a self-adhesive coating
7 denotes an (optional) adhesion promoter layer
8 denotes an (optional) print primer layer
9 denotes the article bearing the applied adhesive tape or label
10, 11, 12, 13 denote regions having different adhesion conditions
14 denotes the part of the label that is removed with the backing; substrate 1
15 denotes the part of the label which remains on the article 9 to be secured
16 denotes customer-specific printing
17 denotes the security label of the invention
18 denotes the part of the layer having optical properties 5 that remains on the article 9 to be secured and exhibits negative recesses in the form of signs
19 denotes the part of the layer having optical properties 5 in the form of positive signs which is removed with the backing substrate 1
In
Applied subsequently, to the layer 3, is a partial release varnish layer 4 which is covered by a layer having optical properties 5. The layer 5 is provided in turn with a self-adhesive coating 6, by which the adhesive tape or label is affixed on the article 9 to be secured.
In
In the region 10, the integrated system separates between the semi transparent metallic or HRI layer 3 and the release varnish layer 4—in other words, the adhesion between the layers 3 and 4 is lower than the adhesion of all other layers to one another and than the adhesion of the self-adhesive coating 6 to the article 9. The layer having optical properties 5 therefore remains in the region 10 in unison with the self-adhesive coating 6 and the release varnish layer 4 on the article 9 to be secured.
In the region 11, the integrated system separates between the layer having optical properties 5 and the self-adhesive coating 6—in other words, the adhesion between the layers 5 and 6 is lower than the adhesion of ail other layers to one another and than the adhesion of the self-adhesive coating 6 to the article 9. The layer having optical properties 5 therefore remains in the region 11 in unison with the stamping/embossing varnish layer 2 and the semitransparent metallic or HRI layer 3 on the removed backing substrate 1.
In the region 12, the integrated system separates between the release varnish layer 4 and the layer having optical properties 5—in other words, the adhesion between the layers 4 and 5 is lower than the adhesion of all other layers to one another and than the adhesion of the self-adhesive coating 6 to the article 9. The layer having optical properties 5 therefore remains in the region 10 in unison with the self-adhesive coating 6 on the article 9 to be secured. In the region 13, the self-adhesive coating 6 parts from the article 9 to be secured—in other words, the adhesion of the self-adhesive coating 6 to the article 9 is lower than the adhesion of all other layers to one another. The layer having optical properties 5 therefore remains in the region 11 in unison with the stamping/embossing varnish layer 2, the semitransparent metallic or HRI layer 3, and the self-adhesive coating 6 on the removed backing substrate 1.
The above adhesion relationships need not necessarily be combined in the manner shown in
It can clearly be seen that in the regions 11 and 13, the self-adhesive coating 6 ends up exposed after the tamper evidence feature has been triggered; in other words, if the surface of the article with the layers that have remained on the article is engaged, the residue 15 in the regions 11 is sticky. In the regions 13, the self-adhesive layer 6 remains on the removed part 14 of the label, and hence the removed part 14 is sticky in the regions 13. It is therefore possible, following triggering of the tamper evidence feature, for the adhesive tape or label to be reaffixed on the article 9, but the tamper evidence is always visible, since the adhesive tape or label can no longer be positioned so precisely that the two parts of the layer having optical properties 5 come to lie congruently with one another again.
| Number | Date | Country | Kind |
|---|---|---|---|
| A 1357/2010 | Aug 2010 | AT | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP11/03834 | 7/30/2011 | WO | 00 | 2/13/2013 |
