EP1291463A1 - Process for producing a selectively metallized foil, and their products - Google Patents

Abstract

To give a selective metallizing to film materials, a carrier substrate (1) is prepared for the application of ink (2) which is partially soluble in a solvent, with recesses in the shape of a negative coding. The printed carrier film is treated by an in-line plasma or corona or flame process. A thin metal layer (4) is applied, and the ink is removed by a solvent combined with a mechanical action. The carrier substrate can be of a plastics or metal film, a nonwoven or paper. The covering layer can be an insulation or an actuator material.

Description

The invention relates to a selectively metallized film, in particular for Use as a security element, especially in value documents, as well a method for producing the selectively metallized film.

From EP-A 0 330 733 are security elements, in particular Security threads consisting of a translucent plastic film, a extending over the entire security element extending opaque Coating, the recesses in the form of the coding to be introduced, especially in the form of characters and patterns known. At least in the areas defined by the recesses can be congruent coloring and / or luminescent substances may be present, through which the coding of the opaque coating under appropriate The influence of light differs in a contrasting color.

From WO 99/13157 security films for securities are known, in which applied to a translucent film, a metallic coating which is not the entire surface in the finished film, but recesses has, which should be clearly visible in transmitted light. The production of this Films take place in that a carrier film with a highly pigmented Printing ink is printed, whereby the paint does not take place over the entire surface, the Printing ink is dried to form a porous paint, then a metallic cover layer is applied and in a further step the highly pigmented ink by washing with a Solvent, optionally removed under mechanical action becomes. Thus, even in those areas where the ink is removed, the metallic cover layer mitzufernt, whereby the transmitted light recognizable recesses are formed. The metallic cover layer has a thickness of 0.01 to 1 .mu.m.

For use as security elements for value documents, in particular banknotes, identity documents and the like, it is necessary that these security elements, for example in thread or tape form as inconspicuous as possible in the carrier, in particular paper or the like, can be integrated. Therefore, it is necessary to strive for the smallest possible thickness of the security elements. Furthermore, however, at the same time a great precision in the dimensions of the recesses to be produced is necessary to ensure sufficient security against counterfeiting, since irregularities in the dimensions of the recesses forming a coding make it difficult to clearly establish the authenticity or any imitation.
Furthermore, it is sometimes also desirable to register corresponding coatings and codings on both sides of the carrier substrate of the security element in order to ensure a mutual identification of the authenticity.

However, this is not sufficient with the methods of the prior art possible because either the thickness is the security element for the desired Application is too large, on the other hand at a smaller thickness sufficient Precision can not be guaranteed.

The object of the invention is therefore to metallized films and a method to To provide their preparation, the disadvantages described above avoids and in particular due to the small thickness and at the same time high precision are particularly suitable as security elements in Value documents to be integrated. In particular, it is the task of Invention a metallized film and a method for their preparation to provide, the film is almost independent of the substrate structured layers of different metals, metal compounds, Alloys or insulators on one or both sides of the carrier substrate optionally, wherein the structured layers accurate registration should be produced.

The invention therefore provides a selectively metallized film by providing a carrier substrate, applying one in one Solvent-soluble partial paint application with recesses in the form of a (negative) coding, treating the printed carrier film by means of a Inline plasma, corona or flame process, applying a thin Covering layer of metals, metal compounds, alloys and / or Insulators and detachment of the paint by the action of a Solvent optionally combined with a mechanical action.

Another object is a method for producing a selectively metallized film, characterized in that on a carrier substrate
in a first step, a paint application which is soluble in a solvent is applied to one or both sides of the carrier substrate
in a second step, this layer is treated by means of an in-line plasma, corona or flame process, and
in a third step, a layer of a material to be structured is applied, which layer may consist of metals, metal compounds, alloys or insulators,
whereupon, in a fourth step, the paint application is removed by means of a solvent, optionally combined with a mechanical action.

By multiple use of this method and accurate register pressure both in the longitudinal and in the side register functional multilayer films being constructed. In principle, this means any number of layers realizable. In particular, also between the individual layers partial or full-surface lacquer and / or film layers are applied.

Under coding are in the following signs, patterns, pictures, lines and understood the same.

For example, carrier foils are preferably flexible plastic foils, for example, from 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 of 5 to 700 .mu.m, preferably 8 to 200 .mu.m, more preferably 12 to 50 .mu.m.
Furthermore, metal foils, for example Al, Cu, Sn, Ni, Fe or stainless steel foils having a thickness of 5-200 μm, preferably 10 to 80 μm, particularly preferably 20-50 μm, may 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, nonwovens, such as continuous fiber webs, staple fiber webs and the like, which may optionally be needled or calendered, can be used as carrier substrates. Preferably such nonwovens consist of plastics, such as PP, PET, PA, PPS and the like, but it is also possible to use nonwovens of natural, optionally treated fibers, such as viscose fiber webs. The nonwovens used have a basis weight of about 20 g / m ² to 500 g / m ² .

The carrier substrates may additionally comprise a lacquer layer which unstructured or structured, for example can be embossed Die Paint layer, for example, an adhesive paint layer or a be releasable transfer lacquer layer, it can by radiation, For example, UV radiation, thermally or reactively crosslinked or crosslinkable and additional properties such as e.g. Scratch-resistant and / or antistatic Have equipment or chemical resistance. Suitable are both aqueous and solvent-containing coating systems, in particular also Lacquer systems based on PE - acrylate, PET acrylate, urethane acrylate, PVC, PMMA or epoxy acrylate.

The carrier substrate can on one or both sides with a hot or Be provided cold seal adhesive or a self-adhesive coating.

In view of the desired properties of the final product for Use as thin as possible security elements are plastic films and Metal foils are particularly preferred for security features in textiles but also suitable for nonwovens.

The surface of the carrier substrate may be structured or unstructured, or for example, be embossed with micro or macrolines, that is on the Surface may optionally have two- or three-dimensional structures to be available.

The application of the paint can be done by any method, for example by gravure printing, flexographic printing, screen printing, digital printing and the like. The color or lacquer used is soluble in a solvent, preferably water, but it is also possible to use a dye soluble in any solvent, for example in alcohol, esters and the like. The color or the colored lacquer can be customary compositions based on natural or artificial macromolecules. The soluble color may be pigmented or unpigmented. As pigments, all known pigments can be used. Particularly suitable are TiO ₂ , ZnS, kaolin and the like.

Subsequently, the printed carrier substrate is treated by means of an in-line plasma (low pressure or atmospheric plasma), corona or flame process. High-energy plasma, for example Ar or Ar / O ₂ plasma, cleans the surface of toning residues of the printing inks. The necessary sharp delimitation of the contours of the recesses, which is necessary for the necessary precision of the coding is achieved. At the same time, the surface is activated. In this case, terminal polar groups are generated on the surface. This improves the adhesion of metals and the like to the surface.

Optionally, simultaneously with the application of the plasma or corona or flame treatment, a thin metal or metal oxide layer can be applied as adhesion promoter, for example by sputtering or vapor deposition. Particularly suitable are Cr, Al, Ag, Ti, Cu, TiO ₂ , Si oxides or chromium oxides. This adhesion promoter layer generally has a thickness of 0.1 nm to 5 nm, preferably 0.2 nm to 2 nm, particularly preferably 0.2 to 1 nm.

As a result, the liability of the partially or fully applied structured functional layer further improved. That's a requirement for the production of functional layers with high precision and good Liability.

Subsequently, the actual functional layer is applied. This layer consists of a metal, a metal compound, an alloy or an insulator. As the metal layer, layers of Al, Cu, Fe, Ag, Au, Cr, Ni, Zn and the like are suitable. 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. As insulators, for example, organic substances and their derivatives and compounds, such as paint and lacquer systems, such as epoxy, polyester, rosin, acrylate, alkyd, melamine, PVA, PVC, isocyanate, urethane, the radiation-curing can be, for example, by heat or UV radiation, suitable.

This functional layer can be prepared by known methods, for example by sputtering, sputtering, printing (gravure, flexo, screen, digital printing and the like), spraying, electroplating and the like. The Thickness of the functional layer is 0.001 to 50 μm, preferably 0.1 to 20 μm.

Subsequently, the ink layer by a suitable solvent, the on the composition of the color layer is matched, removed. Is preferred the paint is water-soluble. Optionally, the replacement by mechanical action are supported.

Also, to further improve the dissolution of the covered ink layer full-surface or precise registration a thin pigmented layer of paint or a pure pigment layer are applied, the thickness of this layer is about 0.01 - 5 microns.

By removing the paint application with those above the paint job Regions of the functional layer, the desired end product is obtained.

According to the method of the invention, the functional layer or in multiple application of the method described the respective functional layers over the entire surface or partially onto the carrier substrate, In particular, the carrier film can be applied.

In multilayer constructions, the layers applied one on top of the other can be used have different properties. It is possible by Combination of different properties of the individual layers, For example, layers with different conductivity, magnetizability, optical properties, absorption behavior and the like structures for Example of security features with several precise authentication features manufacture.

The process steps can be repeated as often as desired, wherein For example, in full-surface application of a functional layer of Color order may be omitted, the inline plasma, corona or

Flame treatment optionally with simultaneous application of a However, adhesion promoter can be advantageous.

Optionally, the thus produced coated film also by a protective lacquer layer are protected or, for example, by laminating or the like further refined.

The metallized films according to the invention are in particular as Security elements, in particular in value documents and data carriers, For example, banknotes, securities, identity documents, cards and used or as security elements or security labels in packaging, textiles, seals and the like.

Due to the excellent precision of the coding and the possibility of following the inventive method also multilayer, very thin films In particular, the films according to the invention are also suitable for producing Embedding in banknotes and the like suitable.

Optionally, the product can be applied with a sealable adhesive, such as a hot or cold seal adhesive to the appropriate substrate, or embedded in paper for security papers by conventional methods, for example.
These sealants can be equipped with visible or visible in the UV light, fluorescent, phosphorescent or laser and IR radiation absorbing features to increase the security against counterfeiting. These features may also be present in the form of patterns or characters or show color effects, in principle any number of colors, preferably 1 to 10 colors or color mixtures, are possible.

The carrier substrate may be used after one-sided coating after application be removed or left on the product. In this case, the carrier film optionally specially equipped on the uncoated side be scratch resistant, antistatic and the like. The same applies to a possible lacquer layer on the carrier substrate.

Fig.1. zeigt eine selektiv metallisierte Folie vor dem Ablösen des Farbauftrags,

Fig. 2 zeigt die selektiv metallisierte Folie nach Ablösen des Farbauftrags.

Fig. 3 zeigt einen selektiv metallisierten Multilayer―Aufbau, Fig. 4 zeigt selektiven Multilayer-Aufbau mit partiellen und vollflächigen Schichten.

The figures show preferred selectively metallized films according to the invention.
In the figures, 1 denotes the carrier substrate, 2 the paint application, 3 the adhesion promoter layer 4 the first functional layer, 3a the second adhesion promoter layer, 4a the second functional layer, 3b the third adhesion promoter layer and 4b the third functional layer.
The functional layers may have different properties as described above.

Fig.1. shows a selectively metallized film before peeling off the paint,

Fig. 2 shows the selectively metallized film after detachment of the paint.

Fig. 3 shows a selectively metallized multilayer structure, Fig. 4 shows selective multilayer structure with partial and full-surface layers.

Examples Example 1:

On a carrier film of PET with a thickness of 12 microns, a water-soluble ink layer based on a thickness of 3 microns is applied by gravure, with recesses are provided in the form of letters.
Subsequently, the printed film is subjected to a low-pressure plasma process with Ar plasma and simultaneously applied a layer of Cr as a primer with a thickness of 0.3 nm.
Then it is steamed with Al. The layer thickness of the vapor-deposited layer is 0.2 μm.
After the process, the film is washed with water and thus the paint application is removed with the adhesion promoter on the paint application and the metal layer located in this area.
The finished product has a selective Al coating with a coding in the form of letters.

Example 2:

On an aluminum foil, a water-soluble ink based on 9 wt% TiO ₂ pigments with recesses in the form of defined lines is applied. Subsequently, the printed film is subjected to a corona process and at the same time a layer of silicon dioxide is applied as a primer with a thickness of 0.3 nm.
Subsequently, the thus treated film is vapor-deposited with Cu, wherein the thickness of the layer is 0.5 microns.
After the process, the film is washed with water and thus the paint application is removed with the adhesion promoter on the paint application and the metal layer located in this area. The film now has a selective metallic coating in the form of defined lines.

Example 3:

A film prepared according to Example 1 is subjected to a plasma treatment with Ar / O ₂ plasma and then printed over the entire surface of a functional layer of a urethane coating system by gravure printing.
Subsequently, the thus treated film is provided with a paint with an alcohol-soluble ink with 10% ZnS as a pigment, wherein partially with the recesses of the first inking overlapping recesses are provided in the form of a pattern. Subsequently, the film is again subjected to a plasma treatment with Ar / O ₂ plasma and simultaneously applied a 0.2 nm thick layer of chromium (III) oxide as a primer. Subsequently, a layer of Al is sprayed with a layer thickness of 0.2 microns. Subsequently, a washing process is carried out with alcohol, which in turn the paint application is replaced with the layers thereon.

Example 4:

It is produced a film analogous to Example 1, although all there described process steps on both sides of the carrier film passer- and be carried out in register. The film thus produced is subsequently with a protective lacquer layer with a fluorescent color in UV light Mistake.

Claims (17)

Selective metallized film made by providing a Carrier substrate, applying a solvent-soluble Partial paint application with recesses in the form of a negative Coding, treating the printed carrier film by means of an in-line plasma, Corona or flame process, applying a thin functional covering layer of metals, metal compounds, Alloys and / or insulators and detachment of the paint by Influence of a solvent optionally combined with a mechanical action. A process for producing a selectively metallized film, characterized in that on a carrier substrate
in a first step, a paint application which is soluble in a solvent is applied to one or both sides of the carrier substrate
in a second step, this layer is treated by means of an in-line plasma, corona or flame process, and
in a third step, a functional layer of a material to be structured is applied, which layer may consist of metals, metal compounds, alloys or insulators,
whereupon, in a fourth step, the paint application is removed by means of a solvent, optionally combined with a mechanical action. A method according to claim 2, characterized in that simultaneously with the plasma, corona or flame treatment, a thin layer of an adhesion promoter is applied. A method according to claim 3, characterized in that a thin layer of a metal, semimetal or their oxide is applied as adhesion promoter. Method according to one of claims 2 to 4, characterized in that are used as carrier substrate plastic or metal carrier films or nonwovens, or papers. Method according to one of claims 2 to 5, characterized in that a paint soluble in water or a water-soluble paint is used as a paint application. A method according to claim 6, characterized in that the water-soluble color or the colored lacquer is pigmented or not pigmented. Method according to one of claims 2 to 7, characterized in that to improve the removability of the paint application over the entire surface or register a thin pigmented ink layer or a pure pigment layer is applied. Method according to one of claims 2 to 6, characterized in that as metal of the functional layer Cu, Al, Fe, Ag, Au, Cr, Ni, Zn, as metal compounds TiO ₂ , Cr-oxides, ZnS, ITO, ATO, FTO , ZnO, Al ₂ O ₃ or silicon oxides, as alloys of Cu-Al, Cu-Zn alloys and as insulators organic substances and derivatives and compounds. Process for producing a multilayer, selectively metallised film, characterized in that the process steps mentioned in claims 2 to 9 are carried out at least twice. A method according to claim 10, characterized in that in the repetition of the process steps mentioned in claims 2 to 9 optionally omitted the process step of the paint application and / or the process step of plasma, corona or flame treatment and / or the process step of applying an adhesion promoter. Method according to one of claims 2 to 11, characterized in that the carrier substrate is scratch-resistant or antistatic on the uncoated side. Method according to one of claims 2 to 12, characterized in that the carrier substrate is provided with an adhesive lacquer layer or release-transfer layer, which may be scratch-resistant and / or antistatic or one or both sides provided with a hot or cold seal adhesive or a self-adhesive coating , Method according to one of claims 2 to 13, characterized in that the surface of the carrier substrate is structured. Selective metallized film produced by a method according to Claims 2 to 14. Use of the selectively metallized film of claim 1 or Claim 15 as a strip or band-shaped security element for Value documents. Use of the selectively metallised film according to claim 1 or 15 for application to a substrate by means of a seal adhesive or for embedding in a carrier material during the manufacturing process of the carrier material.

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