EP1348576A2 - UV laminated security thread - Google Patents

Abstract

The security marking is provided by a strip or band attached to at least one carrier substrate (24,24a), with functional and/or decorative layers, via an adhesive system which is hardened by an electron or UV beam and which is applied to the surface of the security marking in the form of a solution, removed by physical drying. An Independent claim for a method for manufacturing a security marking is also included.

Description

The invention relates to between metallized, transparent, translucent, opaque and / or colored plastic films, cellulose-free or cellulose-containing Papers, paper composites, fabrics or nonwovens embedded or concealed security features in the form of strips, tapes or other Formats, a process for their embedding or lamination, and their Use.

Security features, in particular in the form of threads, tapes or other formats, generally consist of a carrier substrate to which one or more functional and / or decorative layers of various types are applied.
While these functional and / or decorative layers are protected on one side by the carrier substrate, the functional and / or decorative layers are exposed on the other side. It is therefore desirable to laminate these layers before further processing of the security features, for example with a further carrier substrate, which may optionally have one or more further functional and / or decorative layers. In this case, it is particularly important that the lamination process is carried out with a precise registration in order to obtain the required precision and match of the layers of the two substrates.
When embedding such laminated or non-laminated security features between metallized, transparent or translucent plastic films, cellulose-free or cellulose-containing papers, paper composites, fabrics or nonwovens, it is essential to maintain the precision and properties of the security features to ensure authenticity and their verifiability.

According to the known prior art, two or more optionally provided with functional and / or decorative layers Carrier substrates with either a solvent-based or a reactive one solvent-free or a self-adhesive system or by means of Extrusion coating laminated together or between the above mentioned layers embedded.

The disadvantage of using solvent-based adhesive systems is that the solvent contained in the adhesive both in the non-laminated functional and / or decorative layers or in the carrier substrate itself can migrate and thereby the functional and / or decorative layers in their properties, their precision, their appearance, e.g. in the color appearance can change. The carrier substrate can by the solvent, for example, in its transparency, its elasticity and the like are impaired and, for example, spotty or brittle become. Furthermore, drying usually has to take place at high temperatures, which can cause the substrate to shrink.

When using solvent-free, mostly reactive drying Adhesive systems make the reaction or drying of the adhesive difficult controllable. In general, the reaction cannot be stopped precisely be, which makes it a drying or curing undesired penetration into the functional and / or decorative layers and to harden the functional and / or decorative layers or possibly even the carrier substrate comes. Neither the curing time, the degree of curing can be precisely controlled. Thereby the functional and / or decorative layers in their Properties, for example in their defined magnetic or electrical properties, in their precision, for example in dimension a coding in the form of pictures, letters, patterns, lines, characters and the like, in appearance, e.g. also in color Appearance, changed again, which makes it more difficult to prove authenticity.

The carrier substrate can in turn by undesired penetration and Hardening of the reactive adhesive system, for example, in its optical or elastic properties are impaired.

In these methods, there is a certain time for curing and the like required, the laminated or embedded product can only be used with considerable time delay to be processed.

When using self-adhesive laminating adhesives, this is usually the case Compliance with the required relatively small thicknesses of the security features a lamination or embedding between metallized, transparent or translucent plastic films, cellulose-free or cellulose-containing papers, Paper bonds, fabrics or fleeces not possible. There is also again the danger that the chemical properties of the Self-adhesive both the functional and / or decorative layers as well the carrier substrate itself will be affected. They also ensure known self-adhesive systems do not have sufficient bond strength between the laminated substrates or with an embedding between metallized, transparent or translucent plastic films, cellulose-free or pulp-containing papers, paper composites, fabrics or nonwovens sufficient liability. Furthermore, the self-adhesive coatings are mostly Solvable by heat, which then creates the concealed security features be exposed.

When using the extrusion coating process, too usually insufficient strength of the bond between Security feature and laminating substrate or when embedding between metallized, transparent, translucent, opaque and / or colored Plastic films, cellulose-free or cellulose-containing papers, Paper bound, fabrics or fleeces reached. Furthermore, the Carrier substrate and on the functional ones present on the carrier substrate and / or decorative layers exerted a high thermal load.

In addition, when using a Extrusion coating processes usually the required layer thicknesses Security features are not adhered to because Extrusion coating processes usually applied thicker layers Need to become.

The object of the invention was therefore to provide security features, in particular in To provide the form of strips, ribbons and other formats that are compatible with one or more further carrier substrates, optionally further have functional and / or decorative layers, are laminated or between metallized, transparent, translucent, opaque and / or colored plastic films, cellulose-free or cellulose-containing papers, Paper composites, fabrics or fleeces are embedded, to provide which avoided the above-mentioned disadvantages of the known methods become.

The invention therefore relates to security features in the form of Stripes, ribbons and other formats, characterized in that they by means of a radiation-curing, in particular electron-beam or UV-curing Adhesive system with one or more carrier substrates that optionally also have functional and / or decorative layers can, are laminated, or between metallized, transparent, translucent, opaque and / or colored plastic films, cellulose-free or papers containing cellulose, paper composites, fabrics or nonwovens embedded are.

The radiation-curable adhesive system can be, for example radiation-curable adhesive system based on a polyester, one Epoxy or polyurethane system. A UV radiation curable adhesive system contains at least one initiator which, when excited by UV light appropriate wavelength under controlled conditions.

Both radical and cationic systems can be used, which can be hardened in a controlled manner by UV light or by electron beam under defined conditions.
If appropriate, these systems can also contain binders or be dissolved or present as a dispersion. If the systems contain solvents, it is advantageous first to remove the solvent by physical drying and then to carry out the curing or crosslinking.

An example of such a lamination adhesive are, for example Laminating adhesive based on epoxy acrylate

As carrier substrates for both the security features and Carrier substrate to be laminated come, for example, carrier films preferably flexible plastic films, for example made of Pl, PP, MOPP, PE, PPS, PEEK, PEK, PEI, PSU, PAEK, LCP, PEN, PBT, PET, PA, PC, COC, POM, ABS, PVC in question. The carrier films preferably have a thickness 5 - 700 µm, preferably 8 - 200 µm, particularly preferably 12 - 50 µm.

Furthermore, metal foils, for example Al, Cu, Sn, Ni, Fe or stainless steel foils with a thickness of 5-200 μm, preferably 10 to 80 μm, particularly preferably 20-50 μm, can also serve as the carrier substrate. The films can also be surface-treated, coated or laminated, for example with plastics, or painted.
Further, as carrier substrates also paper or composites with paper, for example, composites with plastics with a grammage 20-500 g / m ^2, preferably 40-200 g / m ^2. be used.

Furthermore, woven or non-woven fabrics, such as continuous fiber non-woven fabrics, staple fiber non-woven fabrics and the like, which can optionally be needled or calendered, can be used as carrier substrates. Such fabrics or nonwovens preferably consist of plastics, such as PP, PET, PA, PPS and the like, but fabrics or nonwovens made of natural, optionally treated fibers, such as viscose nonwovens, can also be used. The nonwovens used have a basis weight of approximately 20 g / m ² to 500 g / m ² .

The carrier substrates or the laminating substrates can be functional and / or have decorative layers of any kind.

For example, the carrier or laminating substrates Surface structures, reliefs, metallic, magnetic, electrically conductive, coded or non-coded, optically structured or non-structured, have full or partial layers.

A wide variety of functional and / or decorative layers can be used Color and / or adhesive system compositions are used. The Composition of the individual layers can in particular according to their Task vary, so whether the individual layers exclusively Serve decoration purposes or should represent a functional layer or whether the layer is both a decorative and a functional layer should be.

The layers to be printed can be pigmented or unpigmented. All known pigments, for example inorganic-based pigments such as titanium dioxide, zinc sulfide, kaolin, ITO, ATO, FTO, aluminum, chromium and silicon oxides, or organic-based pigments such as phthalocyanine blue, i-indoline yellow, dioxazine violet and the like can be used as pigments colored and / or encapsulated pigments can also be used in chemical, physical or reactive drying binder systems. Suitable dyes are, for example, 1,1- or 1,2-chromium-cobalt complexes.
Solvent-based paint and / or adhesive systems, aqueous and also solvent-free adhesive systems can be used.
Various natural or synthetic binders can be used as binders.

The functional layers, for example, can have certain electrical, magnetic, chemical, physical and also optical properties exhibit.

For setting electrical properties, for example conductivity for example graphite, carbon black, conductive organic or inorganic Polymers, metal pigments (e.g. copper, aluminum, silver, gold, Iron, chromium and the like), metal alloys such as copper-zinc or Copper-aluminum or amorphous or crystalline ceramic pigments like ITO, FTO, ATO and the like can be added. Furthermore, also doped or undoped semiconductors such as silicon, germanium, Gallium arsenide, arsenic or ion conductors such as amorphous or crystalline metal oxides or metal sulfides can be used as an additive. You can also use it for adjustment the electrical properties of the layer are polar or partially polar Compounds such as surfactants, or non-polar compounds such as silicone additives or hygroscopic or non-hygroscopic salts used or be added. Intrinsically conductive organic polymers can also be used such as polyaniline, polyacetylene, polyethylene dioxythiophene and / or Polystyrene sulfonate can be added.

To set the magnetic properties, paramagnetic, diamagnetic and also ferromagnetic substances, such as iron, nickel, barium, and cobalt or their compounds or salts (for example oxides or Sulfides) can be used. Fe (II) and Fe (III) oxides are particularly suitable, Barium or cobalt ferrites, rare earths and the like.

The optical properties of the layer can be determined by visible colors or pigments, luminescent dyes or pigments that are visible, fluoresce or phosphoresce in the UV or IR range, heat-sensitive colors or pigments, effect pigments, such as liquid crystals, Pearlescent, bronze and / or multilayer color change pigments affect. These can be used in all possible combinations.

Different properties can also be combined by adding different additives mentioned above. It is possible to use colored and / or conductive magnetic pigments. All of the conductive additives mentioned can be used.
All known soluble and non-soluble dyes or pigments can be used especially for coloring magnetic pigments. For example, a brown magnetic paint can be made metallic, for example silvery, by adding metals.

For printing soluble layers, the ink or adhesive system used can be soluble in a solvent, preferably in water, but it is also possible to use an ink which is soluble in any solvent, for example in alcohol, esters and the like. The paint or varnish can be conventional compositions based on natural or artificial macromolecules. The color can be pigmented or unpigmented. All known pigments can be used as pigments. TiO ₂ , ZnS, kaolin and the like are particularly suitable.
If a soluble (partial) color layer is used, this can optionally be removed after applying a further layer in the process according to the invention by means of a suitable solvent which is matched to the composition of the color layer, in order to produce codes in the form of characters and / or patterns of any possible type to be able, as described for example in DE 101 43 523.

However, intermediate layers made of a metal, a metal compound, an alloy or an insulator can also be applied. Layers of Al, Cu, Fe, Ag, Au, Cr, Ni, Zn and the like are suitable as the metal layer. Examples of suitable metal compounds are oxides or sulfides of metals, in particular TiO ₂ , Cr oxides, ZnS, ITO, ATO, FTO, ZnO, Al ₂ O ₃ or silicon oxides. Suitable alloys are, for example, Cu-Al alloys, Cu-Zn alloys and the like. Examples of insulators are organic substances and their derivatives and compounds, for example paint and lacquer systems, for example epoxy, polyester, rosin, acrylate, alkyd, melamine, PVA, PVC, isocyanate, urethane systems, which are radiation-curing can be suitable, for example by heat or UV or electron radiation.

All dyes and pigments can be used individually or in combination with different natural or synthetic binders, e.g. natural oils and resins, such as phenol formaldehyde, urea, melamine, ketone, Use aldehyde, epoxy, polyterpene resins. As an additional binder For example, polyesters, polyvinyl alcohols, polyvinyl acetates, ethers, propionates and chlorides, poly (methyl) acrylates, polystyrenes, olefins, Nitrocellulose, polyisocyanate, urethane systems and others can be used.

All of these layers can be made by known methods, for example by Steaming, sputtering, printing (gravure, flexo, screen, digital, offset and the like), spraying, electroplating and the like can be applied.

Before applying these layers, the material web can be Plasma (low pressure or atmospheric plasma), corona or Flame process are treated. The surface is activated, whereby terminal polar groups are generated on the surface and the Surface is cleaned. This will limit the adhesion of metals, paints and Paint on the surface improved.

If necessary, a thin metal or metal oxide layer can be applied as an adhesion promoter, for example by sputtering or vapor deposition, at the same time as or after the application of the plasma or corona or flame treatment. Cr, Al, Ag, Ti, Cu, TiO ₂ , Si oxides or chromium oxides are particularly suitable. This adhesion promoter layer generally has a thickness of 0.1 nm - 5 nm, preferably 0.2 nm - 2 nm, particularly preferably 0.2 to 1.0 nm.

As a result, the liability of partially or fully applied optionally structured functional layer further improved. This is Prerequisite for the creation of functional layers with high Precision and good grip.

However, a layer which has a surface structure, for example a diffraction structure or a surface relief, can also be applied, this structure preferably being embossed into a radiation-curable lacquer layer.
Furthermore, further layers can be applied by means of known methods, for example direct metallization methods, partial metallization methods in register, over the full area or partially.

These layers can each have encodings or negative encodings in Form of patterns, characters, micro and macro lines, letters, images, mathematically definable line elements, reliefs, guilloches and have machine-readable elements and the like.

The layers applied one above the other can be different Have properties. It is possible by combining different properties of each layer, for example Layers with different conductivity, magnetizability, optical Properties, absorption behavior and the like, for example Manufacture security elements with several precise authenticity features.

For concealing or embedding the security features described above can the individual process steps in different ways be performed.

All known methods are suitable for applying the laminating adhesive, for example by gravure printing, flexographic printing, screen printing, offset printing, Digital printing, smooth roller, screen or line screening processes, each with Co or counter rotation, and the like.

For example, a heated, temperature-controlled tub the radiation-curable adhesive system added and over a Transfer cylinder and via a gravure cylinder on the carrier substrate applied. The viscosity of the Adhesive system precisely controlled. Depending on the used Adhesive system and the carrier substrate used is the Adhesive system application temperature about 20 - 80 ° C, preferably 30 - 60 ° C, particularly preferably 40-50 ° C., adhesive system and Tool temperature should always be at the same level.

It is essential for an even application of the adhesive system that adhesive system to be applied always at precisely controlled temperature and constant purity is maintained and in a steady flow is recorded and applied. In particular, a so-called. Avoid foaming the adhesive system before or during application.

1 shows a device for applying the radiation-curable laminating adhesive. Therein 1 means the carrier substrate, 2 the heated tub, in which the radiation-curable laminating adhesive containing the radiation-curable adhesive system is fed, 3 the immersion cylinder, 4 the transfer cylinder.
2 shows a tub which is particularly suitable for applying the radiation-curable laminating adhesive.
As already mentioned, in order to apply the laminating adhesive evenly, it is necessary to keep it at a constantly precisely controlled temperature and with uniform supply and purity, and in particular to prevent the so-called foaming of the laminating adhesive.
This can be achieved in particular by a special configuration of the laminating adhesive applicator, in particular also the laminating adhesive tub.

Here, the laminating adhesive trough 2, as shown in FIG. 2, consists of a Outer tub 21 and an inner tub 22 with a return plate 22a. 23 means the inflow of the radiation-curable laminating adhesive from one Storage tank 23a via a pump 23b and a filter 23c, 24 means Drainage of the radiation-curable laminating adhesive from the outer tub 22 in the reservoir. 3 means the immersion cylinder and 4 den Transfer cylinder. 25 means a distribution tunnel for the radiation-curable laminating adhesive, 26 the distributor plate of the distributor tunnel.

From a storage container 23a, which is preferably double-walled and is heated to a corresponding temperature of the radiation-curable Setting laminating adhesive is done via a pump 23 b and a fine filter 23c the radiation-curable laminating adhesive into the heated inner tub 22 Laminated adhesive tray 2 promoted. In the inner tub the radiation-curable laminating adhesive via a distribution tunnel 25 and that Distributor plate 26, which is provided with regularly arranged openings, equally distributed. The inner tub has the shape on the inner surface an approximately half cylinder, this surface being dimensioned so that the Immersion cylinder 2 at a defined constant distance from the inner surface the lamination adhesive tray can intervene. Depending on the amount of filling in the The inner tub 22 of the laminating adhesive tub engages with the immersion cylinder with about 1 / 3-1 / 2 its extent in the radiation-curable conveyed into the inner tub Laminating adhesive. The heated inner tub is dimensioned so that them on the heated outside tub from the drain 24 side facing away about the dimension of a half cylinder, however whose shape essentially continues the return plate up to a height from at least half of the diameter to about 2/3 of the diameter of the immersion cylinder.

The immersion cylinder now takes the radiation-curable laminating adhesive out of the Inner tub of the laminating adhesive tub and transfers it to the Transfer cylinder. The excess lamination adhesive is now running, but not is picked up by the transfer cylinder, on the outside of the Inner tub back into the outer tub 21. Likewise runs (in Fig2. Not that part of the laminating adhesive that is applied via the doctor blade 6 (shown in FIG. 1) Laminating adhesive not applied to the gravure cylinder in the outer tub back.

Due to the orientation of the outer tub not flat in one level but with a slight slope from the side of the drain facing away from the drain Laminating adhesive tray to the side on which the drain is located, that in the Outside tub 21 collected laminating adhesive from the whole Laminating adhesive applicator guided back into the reservoir 23a. In the inner tub is therefore always only from the storage container below defined temperature and with that defined by the pump 23 b Laminating adhesive introduced into the flow rate.

By avoiding the return of not over the following cylinders and the squeegee applied in the inner tub becomes the The temperature of the lamination adhesive in the inner tub was kept correctly constant and also a so-called foaming of the laminating adhesive through the introduction of air avoided. Furthermore, the temperature of the laminating adhesive in the inner tub constantly controlled by a temperature sensor (not shown in Fig.2) Laminating adhesive can therefore be applied with excellent uniformity take place under defined conditions.

3, 4 and 5 are different according to the invention Laminating process shown.

24 and 24a each represent a substrate, 25 a dryer, 26, 26a, 26b and 26c the radiation sources for curing or crosslinking the Laminating adhesive and 27 the laminating gap.

In a first method (FIG. 3) the corresponding one is described above radiation-curable laminating adhesive on the surface of the security feature, for example, as described above. If the lamination adhesive contains a solvent, then by physical drying the solvent removed. Then by a suitable Radiation source depending on the laminating adhesive used Curing or networking initiated and then the Laminated film applied.

In a further method (Fig. 4) the corresponding one above described radiation-curable laminating adhesive on the surface of the Security feature applied, possibly an existing one Solvent removed by physical drying, and then that Substrate and the lamination film in a lamination nip and printing merged, while at the same time by a corresponding Radiation source, the lamination adhesive is cured or crosslinked.

In a third method (FIG. 5) the corresponding one is described above radiation-curable laminating adhesive on the surface of the security feature applied, optionally by any solvent present physical drying removed, and then the substrate and the Laminating film in a laminating gap and printing merged, whereupon then the hardening or The laminating adhesive is cross-linked through the substrate. In this Case must use at least that when using a UV-curable laminating adhesive Substrate through which the lamination adhesive is irradiated and cured transmissive for the corresponding wavelength of UV light or be transparent. When using an electron beam curable Such a transparency is not necessary for laminating adhesive systems.

The lamination or embedding of the Starting material.

As a radiation source for UV-curable laminating adhesives in the short-wave range Hg lamps are suitable, for example, Hg lamps doped in the long-wave range, especially Ga, Fe, Ga / Pb doped Hg lamps.

The kinetics of crosslinking is controlled by temperature control, in particular by the guidance of the substrate to be laminated via temperature-controlled Rolls past the lamination gap, checked.

The laminating or embedding temperature is preferably in Dependence on the adhesive system used and the required lamination or embedding speed about 20-150 ° C.

The lamination or embedding process is preferably carried out under one Pressure of about 0 - 1000 N / mm.

This ensures a very fast and safe adhesion and Embedding achieved. The product laminated in this way is immediately processable and can be printed, coated or on immediately afterwards, for example processed in a similar manner.

All other cylinders and rollers provided in the device are in Depending on the laminating adhesive system used, an exact Subjected to temperature control.

Claims (7)

Security features in the form of strips, tapes and other formats, characterized in that they are laminated or, respectively, laminated by means of a radiation-curing, in particular electron beam or UV-curing, adhesive system with one or more carrier substrates, which may also have functional and / or decorative layers embedded between metallized, transparent, translucent, opaque and / or colored plastic films, cellulose-free or cellulose-containing papers, paper composites, fabrics or nonwovens. Security features according to claim 1, characterized in that a UV curing adhesive system is used. Security features according to claim 1, characterized in that an electron beam curable adhesive system is used A method for producing the security features according to claim 1, characterized in that the adhesive system is applied to the surface of the security feature, then any solvent that may be present is removed by physical drying, the adhesive system is cured or crosslinked by irradiation with a suitable radiation source, and then subsequently with a Carrier substrate is laminated. A method for producing the security features according to claim 1, characterized in that the adhesive system is applied to the surface of the security feature, then any solvent that may be present is removed by physical drying, then using a carrier substrate with simultaneous curing or crosslinking of the adhesive system by irradiation with a suitable one Radiation source is concealed. A method for producing the security features according to claim 1, characterized in that the adhesive system is applied to the surface of the security feature, then any solvent that may be present is removed by physical drying, then laminated with a carrier substrate, whereupon the curing or crosslinking of the adhesive system by irradiation with a suitable radiation source. Use of the security features according to one of claims 1 or 2 for application or embedding in data carriers and / or Valuable documents and / or packaging.

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