DE102017223464A1 - Temperature-resistant laser-inscribable film - Google Patents

Abstract

A laser-writable film comprising a contrast layer based on a cured acrylate paint composition and an engraving layer disposed above the contrast layer, the cured acrylate paint composition comprising on a composition comprising 30 to 80% by weight of a trifunctional oligomer A, 0 to 20% by weight of a trifunctional monomer B, 1 to 30 wt .-% of a difunctional monomer C, and 2 to 40 wt .-% of a coloring pigment based, further comprising a below the contrast layer disposed latent reactive adhesive layer containing a thermoplastic component having a melting temperature T (melt ) having 35 ° C ≤ T (melt) ≤ 90 ° C and containing functional groups which can react with isocyanate, and an isocyanate-containing component which is particulate, in particular finely particulate, dispersed in the thermoplastic component and blocked, microencapsulated or in the area of particle surface is substantially deactivated, wherein the particles have a light-off temperature T (light off) of 40 ° C ≤ T (light off) ≤ 120 ° C, and wherein T (light-off) ≥ T (enamel), has a good long-term temperature resistance, good chemical Resistance and a high counterfeit security.

Description

The present invention relates to a laser writable film comprising a contrast layer based on a cured acrylate paint composition, wherein the cured acrylate paint composition is based on a composition comprising 30 to 80% by weight of a trifunctional oligomer A; 0 to 20% by weight of a trifunctional monomer B; 1 to 30% by weight of a difunctional monomer C; and 2 to 40% by weight of a coloring pigment is based; and an engraving layer disposed above the contrast layer, and laser-writable labels made of the film. The present invention further relates to a process for producing a laser-writable film and to the use of the produced films and labels.

The labeling of objects is becoming increasingly important. For example, in the automotive industry, conventional printed labels are replaced by laser-writable labels. With the help of laser-writable labels, information and instructions such as tire pressure or fuel type are placed on various components of motor vehicles. In addition to such indications, laser-writable labels may also include security information such as chassis and vehicle identification numbers. Corresponding labels allow in the case of theft or accident, a conclusion on vehicle and manufacturing stages in its manufacture. The use of special security features such as holograms, permanent UV prints (foot print) on the substrate on which the label was glued, and targeted selection of materials of the laser-writable labels serve on the one hand to make it difficult to imitate the material and on the other hand display manipulation attempts.

Laser-writable labels are known from the prior art, which can be written quickly, allow a high contrast of registered characters and ensure high temperature resistance over short periods of time. DE 81 30 861 U1 discloses multilayer labels containing a thin and a thick lacquer layer and withstanding high temperatures for short periods of time. DE 100 48 665 A1 and DE 101 42 638 A1 describe laser-inscribable labels that also withstand high temperatures for short periods of time.

In the case of longer-lasting temperature influences, however, the labels of the prior art lead to a contraction ("shrinkage") of one or more layers. There is a presumption that this contraction is caused by a change in the areal extent of one or more layers. The contraction of one or more layers within known labels manifests itself in a detachment of the labels in the region of their edges. In the case of sensitive data such as VINs, this detachment poses a safety issue in itself, as labels could possibly be completely removed undamaged and residue-free. On the other hand, contractions can lead to tensions within the label if the expansion behavior of different layers within a label behaves differently with increasing temperature or if chemical processes lead to shrinkage within a layer. This can be caused, for example, by aging processes, such as crosslinking reactions. In the case of such tensions, cracking occurs within the labels, which on the one hand does not sufficiently take account of aesthetic requirements, on the other hand a manipulation attempt could be erroneously suspected.

Against the background of increasing demands on the temperature resistance of laser-inscribable labels for extended periods of time, there has been a demand for improved films which serve as starting material for corresponding laser-inscribable labels. All known from the prior art laser-writable labels and films met the increasing demands on tamper resistance and high temperature resistance only partially. In particular, at high temperature, the known labels lost the dimensional stability of one or more layers, which manifests itself in a contraction or "shrinkage", as well as an associated edge lifting of the labels, as well as cracking.

The DE 2011080803 A1 discloses in this context laser-writable films which can serve as starting material for the production of dimensionally stable laser-inscribable labels and in which the chemical resistance is maintained or improved in comparison to prior art labels. Such films have a contrast layer based on a cured acrylate paint composition based on a composition comprising 30 to 80% by weight of a trifunctional oligomer A, 0 to 20% by weight of a trifunctional monomer B, 1 to 30% by weight of a difunctional Monomers C and 2 to 40 wt .-% of a coloring pigment, based.

For the application of the film or of the labels produced therefrom, the laser-inscribable film has a PSA layer below the contrast layer.

In this case, suitable adhesive PSAs are all typical adhesives which have a high bond strength and high tack, in particular acrylate adhesives, for example resin-modified acrylate adhesives, natural rubber adhesives and synthetic rubber adhesives.

It has now been found that the adhesives which are used according to the prior art for the films and labels, unfortunately, are not suitable for reliably and consistently bonding them. Especially with structured substrates, in which a relatively thick adhesive layer must be applied in order to achieve a sufficiently good bond strength, it has been found that it is possible, due to the thickness of the layer of adhesive, to remove the film or label by cutting the layer of adhesive layer, without destroying it. Thus, the security against counterfeiting can not be guaranteed. Further, the prior art films have not been able to meet the long-term requirements for temperature resistance in the automotive industry.

The present invention therefore an object of the invention to provide a laser-writable film available that can be easily and safely adhered to different surfaces, the film is not forgery-proof and can not be detached from the ground without damage. The film must also meet the requirements of the automotive industry for long-term temperature stability (150 ° C, 1,600 weeks) and be resistant to chemicals, especially liquids commonly used in the automotive industry such as gasoline or brake fluid.

This object is achieved with a film of the type mentioned in that it further comprises at least one, preferably just one, disposed below the contrast layer adhesive layer, wherein the adhesive layer is a latent reactive adhesive layer comprising a thermoplastic component having a melting temperature T (enamel) having 35 ° C ≤ T (melt) ≤ 90 ° C and contains functional groups which can react with isocyanate, and an isocyanate-containing component which particulate, especially finely particulate, is dispersed in the thermoplastic component and blocked, microencapsulated or is substantially deactivated in the region of the particle surface, wherein the particles have a light-off temperature T (light off) of 40 ° C ≤ T (light off) ≤ 120 ° C, and wherein T (light-off) ≥ T (enamel) contains. Particulate particulate means having a particle size distribution with d ₅₀ <50 microns, wherein the particle size distribution is preferably <15 microns.

Such a film meets the requirements for high security against counterfeiting, since no destructive detachment from the substrate is possible, in terms of long-term temperature resistance, that is, even at temperatures of 150 ° C for 1,600 weeks are no detachments, shrinkages, cracks or the like. determine as well as chemical resistance. The film is therefore outstandingly suitable for use as a tamper-proof, laser-inscribable film in various fields, in particular in the automotive industry.

By chemical resistance is meant in this sense, for example, the resistance to hydrocarbons such as fuels for motor vehicles and solvents, which could possibly come into contact with the labels.

For the purposes of this application T (enamel) is the melting temperature of the thermoplastic component and T (Anspring) is the temperature at which the isocyanate groups of the particles dispersed in the thermoplastic component are enabled to react with the functional groups of the thermoplastic polyurethane (For example, because they are distributed in the matrix with the thermoplastic polyurethane). In the case of blocked isocyanate groups, T (light off) is the deblocking temperature, in the case of microencapsulation the release of isocyanate from the microcapsules (for example by melting the microcapsule shell) and in the case of isocyanates deactivated in the region of the surface of the isocyanate particles, a melting of the isocyanate particles , For the purposes of this invention, all blocked, microencapsulated or in the region of the particle surface deactivated isocyanate-containing systems known from the prior art are conceivable which fulfill the specifications for T (Anspring). The thermoplastic polyurethanes and the isocyanate-containing component are preferably dispersible in an aqueous medium or dispersed in an aqueous medium.

Melting temperatures are determined by differential scanning calorimetry (DDK, DSC) DIN 53765-B-10 (1994). The determination of T (Anspring) also takes place by means of differential scanning calorimetry (DDK, DSC). The exothermic signal in the thermogram becomes the first Evaluated heating curve at a heating rate of 10 K / min, which corresponds to the reaction of the isocyanate groups, evaluated. The onset temperature of this signal is used as T (light-off).

In a preferred embodiment of the present invention, the composition on which the acrylate paint composition is based comprises 50 to 60% by weight, preferably 52 to 58% by weight of the trifunctional oligomer A, 5 to 15% by weight, preferably 8 to 12% by weight The amount of the coloring pigment within the acrylate lacquer compositions of preferred embodiments depends on the type of material used. In the case of carbon black as a coloring pigment, for example, 2 to 7 wt .-% are preferred, while in the case of TiO ₂ preferably 15 to 40 wt .-%, particularly preferably 22 to 28 wt .-% are used. The trifunctional oligomer A, the trifunctional monomer B and the difunctional monomer C are also referred to below as component A, component B or component C. Surprisingly, it has been found that compositions containing the components A, B and C and the coloring pigment in the stated amount give especially thermally stable cured acrylate lacquer compositions.

The engraving layer is a layer arranged above the contrast layer, which can be labeled with the aid of a single laser beam or with the aid of a plurality of laser beams. In this labeling process, the engraving layer is ablated at the points to which a laser beam is directed with appropriate energy. With sufficient energy input, the engraving layer is locally completely removed, so that it is translucent at these points. It is also conceivable that the engraving layer is only partially ablated in some places, so that an opaque appearance of the engraving layer results at these locations. The engraving layer is preferably a lacquer layer which can be applied by means of printing processes. Preferred examples of corresponding print varnish layers include printing varnishes based on electron beam-curable or UV-curable acrylate varnishes. In an alternative embodiment of the invention, the engraving layer consists of a thin metal layer. The engraving layer preferably has a thickness of 1 to 30 μm, preferably 1 to 20 μm, particularly preferably 1 to 10 μm. If the thickness of the engraving layer moves in this range, the provision of a particularly temperature-resistant laser-writable film is possible. In comparison with the contrast layer, which preferably has a thickness of 20 to 300 μm, preferably 40 to 200 μm, particularly preferably 60 to 150 μm, the thickness of the engraving layer is preferably for example 10% of the thickness of the contrast layer or less.

The contrast layer of films of the invention comprises a cured acrylate paint composition based on a composition comprising 30 to 80 wt .-%, preferably 50 to 60 wt .-%, particularly preferably 52 to 58 wt .-% of a trifunctional oligomer A, 0 to 20 wt. -%, preferably 5 to 15 wt .-%, particularly preferably 8 to 12 wt .-% of a trifunctional monomer B, 1 to 30 wt .-%, preferably 5 to 15 wt .-%, particularly preferably 8 to 12 wt. % of a difunctional monomer C and 2 to 40% by weight of a coloring pigment. The contrast layer of films of the invention can be provided by curing a composition comprising components A, B and C and the coloring pigment. For this purpose, the composition by means of UV radiation, electron beam curing (hereinafter ESH) or thermally crosslinked. Preferably, the crosslinking takes place by means of ESH.

The contrast layer of films according to the invention comprises at least one coloring pigment. Coloring pigments in the context of the present invention include, without limitation, all coloring pigments which are used as dyes and / or brighteners in paints and varnishes. Examples of coloring pigments are the titanium dioxide in the rutile modification ("TiO 2", for example rutile types from Kronos), carbon blacks (for example Printex grades from Evonik) or other color pigments known to the person skilled in the art, as described, for example, in the textbook of coatings and coatings Bd. 5 (Hans Kittel and Jürgen Spille, Hirzel Verlag (Stuttgart), 2003). The coloring pigment is preferably pigments which are as stable as possible to weathering. Particularly preferred for the contrast layer is titanium dioxide in the rutile modification. Essential to the invention is not the color of the pigment or the contrast layer per se, but the difference in color or contrast compared to the engraving layer. The pigment used in the invention serves to adjust the contrast, which after the lettering of the film, i. after ablation of the engraving layer is generated by means of laser between the contrast layer and the engraving layer.

The trifunctional oligomer A is an oligomer having three unsaturated (meth) acrylate units per molecule, whose number-average molecular weight Mn (determined by GPC, calibration with polystyrene standard) is preferably between 1000 and 5000 g / mol, preferably between 1400 and 3600 g / mol. preferably between 1800 and 2200 g / mol, more preferably between 1900 and 2100 g / mol. Is the molecular weight Mn in the stated range, this has a positive influence on the long-term temperature resistance of the cured acrylate paint composition, so that particularly dimensionally stable contrast layers can be obtained.

In a preferred embodiment, the trifunctional oligomer A is selected from the group of polyurethane tri (meth) acrylates and polyester tri (meth) acrylates, of which polyurethane tri (meth) acrylates are particularly preferred. The term (meth) acrylate includes acrylates, methacrylates and mixtures thereof. The trifunctional oligomer A is preferably a polyurethane tri (meth) acrylate, more preferably a polyurethane triacrylate. Polyurethane tri (meth) acrylates are oligomers each containing three unsaturated (meth) acrylate groups per molecule and several, i. at least two urethane units. Examples of preferred polyurethane triacrylates are the aliphatic urethane triacrylates CN9260D75® and CN9278D80® from Sartomer, of which CN9260D75® is particularly preferred.

wobei R in Formel I Wasserstoff oder eine Methylgruppe darstellt; A Wasserstoff oder eine Ethylgruppe ist; X, Y und Z jeweils unabhängig voneinander eine Propylen- oder Ethylen-Einheit darstellen; und a, b und c jeweils unabhängig voneinander eine ganze Zahl von 1 bis 4, bevorzugt 1 bis 3 sind, und a+b+c eine Zahl zwischen 3 und 12, bevorzugt von 3 bis 9 darstellt. In einer besonders bevorzugten Ausführungsform der Erfindung sind X, Y und Z Propyleneinheiten. Besonders bevorzugt ist das trifunktionelle Monomer ein propoxyliertes Glyceroltriacrylat. Wird das trifunktionelle Monomer B so ausgewählt, dass das Molekulargewicht in die oben genannten Bereiche und/oder dass das Monomer B unter die oben genannte Formel I fällt, so übt auch die Komponente B einen positiven Einfluss auf die Temperaturbeständigkeit der Kontrastschicht und somit der laserbeschriftbaren Folie aus.The trifunctional monomer B contains three unsaturated (meth) acrylate units per molecule and in a preferred embodiment of the invention has a molecular weight of 300 to 1000 g / mol, preferably 350 to 800 g / mol, preferably 350 to 600 g / mol, particularly preferably 400 up to 450 g / mol. Component B is preferably selected from the group consisting of propoxylated and ethoxylated glycerol tri (meth) acrylates and propoxylated and ethoxylated trimethylolpropane tri (meth) acrylates of the general formula (I) or mixtures thereof:

wherein R in formula I represents hydrogen or a methyl group; A is hydrogen or an ethyl group; X, Y and Z each independently represent a propylene or ethylene moiety; and a, b and c are each independently an integer from 1 to 4, preferably from 1 to 3, and a + b + c is a number from 3 to 12, preferably from 3 to 9. In a particularly preferred embodiment of the invention, X, Y and Z are propylene units. Most preferably, the trifunctional monomer is a propoxylated glycerol triacrylate. When the trifunctional monomer B is selected such that the molecular weight falls within the above-mentioned ranges and / or that the monomer B falls within the above-mentioned formula I, the component B also positively influences the temperature resistance of the contrast layer and hence the laser-writable film out.

und der Propylenglykoldiacrylate der allgemeinen Formel (III):

oder Mischungen hieraus, wobei n in den Formeln II und III jeweils unabhängig voneinander eine ganze Zahl von 1 bis 15, bevorzugt von 1 bis 9, besonders bevorzugt von 2 bis 6 und ganz besonders bevorzugt 3 oder 4 darstellen. In einer besonders bevorzugten Ausführungsform der vorliegenden Erfindung ist das difunktionelle Monomer C Triethylenglykoldiacrylat. Wird das difunktionelle Monomer C so ausgewählt, dass das Molekulargewicht in die oben genannten Bereiche und/oder dass das Monomer C unter die oben genannte Formel II oder III fällt, so übt auch die Komponente C einen positiven Einfluss auf die Temperaturbeständigkeit der Kontrastschicht und somit der laserbeschriftbaren Folie aus.The difunctional monomer C is a monomer having two unsaturated acrylate units per molecule. Component C preferably has a molecular weight of 100 to 1000 g / mol, preferably 180 to 350 g / mol, more preferably 220 to 280 g / mol, and is preferably selected from the group of the ethylene glycol diacrylates of the general formula (II):

and the propylene glycol diacrylates of the general formula (III):

or mixtures thereof, wherein n in the formulas II and III are each independently an integer from 1 to 15, preferably from 1 to 9, more preferably from 2 to 6 and most preferably 3 or 4 represent. In a particularly preferred embodiment of the present invention, the difunctional monomer C is triethylene glycol diacrylate. If the difunctional monomer C is selected such that the molecular weight falls in the abovementioned ranges and / or that the monomer C falls under the abovementioned formula II or III, then the component C also has a positive influence on the temperature resistance of the contrast layer and thus the laser-writable film.

In a particularly preferred embodiment of the invention, the contrast layer is based on a composition comprising at least one polyurethane triacrylate, preferably CN9260D75® or CN9278D80® from Sartomer as component A, a propoxylated glycerol triacrylate of the formula I given above as component B, triethylene glycol diacrylate as component C and a pigment For example, titanium dioxide in the rutile modification.

The latent-reactive adhesive layer is preferably based on the so-called 1K latentreaktivem polyurethane obtained from aqueous polyurethane dispersion, preferably Dispercoll® U ^® from. Bayer AG. The latent-reactive adhesive films contain a thermoplastic component which has a melting temperature, T (melt), and contains functional groups capable of reacting with isocyanate, and an isocyanate-containing component which is particulate, in particular finely particulate, dispersed in the thermoplastic component and is essentially deactivated in the area of the particle surface. Particulate particulate means having a particle size distribution with d ₅₀ <50 microns, wherein the particle size distribution is preferably <15 microns.

The particles have a light-off temperature, T (light-off), for which T (enamel) ≦ T (light-off) applies. T (enamel) is between 35 ° C and 90 ° C, preferably between 40 ° C and 60 ° C. T (Anspring) is between 40 ° C and 120 ° C, preferably below 100 ° C, most preferably below 90 ° C. As lower limit, 50 ° C is preferred and 60 ° C is particularly preferred. The latent-reactive adhesive films are not tacky at room temperature, so that a good (re-) positionability is ensured before thermal initiation and the buildup of the adhesive strength of the bond is started.

T (enamel) <T (light-off) is particularly preferred, since such an unintentional triggering of the crosslinking reaction in the preparation of the web-shaped adhesive product can be reliably avoided.

The thermoplastic components used are preferably those compounds which are functionalized with OH and / or NH ₂ groups. Very preferably, the thermoplastic component is at least one semicrystalline polyester polyurethane.

The latently reactive adhesive layer preferably contains an anionic, high molecular weight polyurethane dispersion as thermoplastic component which has a melting temperature (in dried form) T (melt) with 35 ° C. ≦ T (melt) ≦ 90 ° C., in particular 40 ° C. ≦ T ( Schmelz) ≤ 60 ° C, and contains functional groups that can react with isocyanate, for example in the form of commercially available products from the above-mentioned Dispercoll U family; such as Dispercoll U53, Dispercoll U54, Dispercoll U56, Dispercoll U 8755, Dispercoll U XP 2815, Dispercoll VP KA 8758, Dispercoll U XP 2682, Dispercoll U 2824 XP, Dispercoll U XP 2701, Dispercoll U XP 2702, Dispercoll U XP 2710 and / or Dispercoll BL XP 2578 (Dispercoll is a registered trademark of Bayer AG).

In addition, the latent-reactive adhesive layer preferably contains toluene diisocyanate compounds (TDI compounds), such as Dispercoll BL XP 2514 (TDI dimer) and / or Aqualink U (dispersion of blocked TDI dimer) and / or isophorone diisocyanates (IPDI) , such as Aqualink D (dispersion of blocked IPDI trimer) as an isocyanate-containing component which is particulate, in particular finely particulate, dispersed in the thermoplastic component and is blocked, microencapsulated or substantially deactivated in the region of the particle surface. The diisocyanates are used, for example, in the form of the aqueous suspensions of the respective latent-reactive solid isocyanate. Aqualink is offered by the company Aquaspersions. In particular in combination with anionic, high molecular weight polyurethane dispersions as a thermoplastic component (such as the aforementioned Dispercoll U products), the abovementioned diisocyanate products can be used as crosslinking component. Other isocyanates, including monomeric and oligomeric compounds and polyisocyanates, can be used.

The latent-reactive adhesive layer may further contain additional formulation ingredients. These include thickeners, wetting agents, defoamers, fillers (for example, thermally conductive), pigments, catalysts, anti-aging agents, light stabilizers and other polymers for setting special adhesive properties. Special adhesive properties can be adjusted, for example, by admixing aqueous dispersions of amorphous polymers (for example polyether urethanes or polyacrylates) and / or by admixing aqueous resin dispersions (in particular based on rosin esters) or liquid resins.

Preferably, the latent-reactive adhesive layer is not tacky at room temperature.

According to the invention, the at least one latently reactive adhesive layer has a layer thickness of at least 10 μm to at most 500 μm, preferably from at least 15 μm to at most 250 μm, and very particularly preferably from 20 μm to at most 35 μm.

The present invention further relates to laser-writable labels made from the film. This is done in cutting or punching processes. Since the laser-writable film according to the invention has an adhesive layer, labels can be obtained by a punching or cutting step, which can be applied as such directly to different substrates without having to undergo a further coating step in ready-made form.

1. i) Bereitstellen einer Stützfolie;
2. ii) Aufbringen der Gravierschicht auf die Stützfolie;
3. iii) Aufbringen einer Acrylatlackzusammensetzung umfassend die Komponenten A, optional B, C sowie das farbgebende Pigment auf die Gravierschicht;
4. iv) Härten der Acrylatlackzusammensetzung, um die Kontrastschicht zu erhalten;
5. v) Aufbringen der latentreaktiven Klebeschicht auf die Kontrastschicht sowie das Bedecken der Klebemasse mit einem Trennpapier oder ähnlichem Release-Liner;
6. vi) und das Entfernen der Stützfolie.

Laser-writable films according to the invention can be produced in various ways. However, in a preferred embodiment, the present invention relates to methods of making laser writable labels comprising the steps of:

1. i) providing a support film;
2. ii) applying the engraving layer to the backing sheet;
3. iii) applying an acrylate paint composition comprising components A, optionally B, C and the coloring pigment to the engraving layer;
4. iv) curing the acrylate paint composition to obtain the contrast layer;
5. v) applying the latent-reactive adhesive layer to the contrast layer and covering the adhesive with a release paper or similar release liner;
6. vi) and the removal of the support film.

In this process, conventional films based on various materials such as polyethylene terephthalate (PET) can be used as the backing film, which may also be referred to as process liner. The application of both the engraving layer to the backing film and the acrylate paint composition to the engraving layer can be effected by means of conventional printing and coating methods. In a preferred embodiment of the invention, the acrylate lacquer composition is applied by means of a comma bar.

Preferably, the adhesive layer is laminated in the form of a film to the film consisting of engraving layer and contrast layer. The adhesive layer film preferably has a weight per unit area of from 10 g / m ² to 100 g / m ² , preferably from 15 g / m ² to 75 g / m ² , particularly preferably from 20 g / m ² to 60 g / m ² , and in particular from 25 g / m ² to 50 g / m ² , on.

Finally, the present invention relates to the use of the produced films and labels in the automotive industry.

Surprisingly, it has been found that laser-writable films which can be produced by the process described and comprise a contrast layer based on the described acrylate paint composition according to the invention have increased long-term temperature resistance compared to known films and labels of the prior art. Thus, the film of the invention meets in particular the requirements of GB standard GB / T 25978 for long-term temperature resistance (150 ° C, 1,600 weeks). This increased long-term temperature resistance manifests itself in a suppressed edge lifting of the films and labels which have been applied to a substrate by means of an adhesive, and in a reduced tendency to crack during long-term adhesion in the bonded state to the substrate. Surprisingly, films and labels according to the invention with improved temperature resistance continue to provide excellent protection against tampering because, in spite of their temperature stability, they break in the region of the contrast layer in the case of a manipulation attempt, for example during a detachment attempt in the bonded state from a substrate. This breaking manifests itself visibly outwardly in the form of a clearly recognizable crack formation. As a result, the labels according to the invention only display manipulation attempts if corresponding tests have also taken place.

In the following the invention will be explained in more detail by means of an example. Unless otherwise indicated, all amounts in the following examples are parts by weight based on the total composition.

Production of the patterns

For the production of samples of laser-resistant films, in the following Examples 1 and 2, first a 50 μm thick polyester film as a support carrier film on a UV flexographic printing machine SMB at a Bahngeschwingikeit of 15 m / min with Flexocure Gemini (black) from Flint to produce a Engraving layer printed, so that the pressure level was between 2 and 4 microns. Subsequently, the thus obtained coating for the production of the engraving layer was UV-cured using a Hg-spotlight tube of the type E 70-2 (4) x1 BLK-2-SLC from IST Metz GmbH. The radiator output of the radiator tube was 80 W / cm.

To prepare the contrast layer were 55 parts CN 9260® Trifunctional urethane acrylate (oligomer) from Sartomer, M _n 2000 g / mol 10 parts SR9020® Trifunctional acrylate (reactive diluent) from Sartomer Propoxylated glyceryl triacrylate, M _n 428 g / mol 10 parts SR 272Ⓡ Difunctional acrylate (reactive diluent), from Sartomer triethylene glycol diacrylate, M _n 258 g / mol 25 parts Kronos 2160Ⓡ Titanium dioxide in a Dispermaten (dissolver CN10 from VMA Getzmann) with water-cooled dispersing tank (volume 11) and a 60mm dissolver disc and homogenized at a temperature of 40 ° C for 20 minutes at 8000 U / min. The composition thus obtained was applied to the engraving layer by means of a doctor blade in a layer thickness of 100 μm and crosslinked by electron beam curing at 80 kGy and 240 kV to give the contrast layer.

• Beispiel 1: eine einseitig mit einem Releaseliner ausgestattete, 40 µm dicke Acrylathaftklebemasse (s.u.) aufgebracht, bevor die Polyester-Stützträgerfolie abgezogen wurde;
• Beispiel 2: einen latenreaktiven Klebefilm laminiert.

The thus obtained composite of support carrier film / engraving layer / contrast layer was on

• Example 1: a one-sided equipped with a release liner, 40 micron thick Acrylathaftklebememasse (see below) applied before the polyester backing sheet was peeled off;
• Example 2 Laminated a Latenreaktive Adhesive Film.

The resulting film was laser marked using a Rofin Nd: YAG solid state laser 50D with a test print and a bar code and also cut into 3 x 8 cm labels using this laser.

Preparation of Acrylic Adhesive Composition Example 1

The pressure-sensitive adhesive used was a resin-modified acrylate adhesive which consisted of 80% by weight of an acrylate copolymer and 20% by weight of terpene-phenolic resin. The copolymer was obtained by polymerization of 47.5% by weight of n-butyl acrylate, 47.5% by weight of 2-ethylhexyl acrylate, 2% by weight of glycidyl methacrylate and 1% by weight of acrylic acid;

Preparation of Latent Reactive Adhesive Film Example 2

A latent-reactive adhesive film was prepared from 100 parts Dispercoll U53 (Bayer AG), 10 parts Dispercoll BL XP 2514 (Bayer AG) and 1.5 parts Borchigel 0625 (OMG Borchers). The formulation ingredients were mixed as an aqueous dispersion in a barrel with an anchor stirrer at 60 rpm for a period of 15 minutes at room temperature. The solids content was adjusted to 46% by weight by adding demineralized water.

By means of a web coating system, a coating on a temporary carrier in the form of a one-side pretreated polyester film (PET in 50 .mu.m thick type Hostaphan GN4600A Mitsubishi) was produced by means of a doctor blade.

It was then freed from water in a drying tunnel at 40 ° C for 15 min. Resulting bales were cut into rolls 50 mm wide and 100 m long. The samples had a layer thickness of the latent-reactive adhesive film of 40 μm.

Test Methods

To determine the temperature resistance and the tamper resistance, five labels each of the samples obtained according to Examples 1 to 4 were examined. The procedure was as follows.

Temperature resistance:

The laser label is affixed bubble-free to a 1 mm thick steel plate painted with a solvent-based clear coat of Kansai Paint (KINO 1210TW-2). After about 24 hours of waiting at room temperature, the sample is stored at 150 ° C for a period of 2300 hours.

At the end of the storage period the sample is checked for edge release (the detachment of the edge of the label from the substrate in mm - measured from the edge of the label) and the number of cracks in the label. In addition, the shrinkage of the samples is measured (in% of the original bond area).

• 1, dass das Kantenabheben weniger als 0,1 mm und der Schrumpf weniger als 0,5% beträgt; ferner sind keine Risse sichtbar;
• 2, dass das Kantenabheben weniger als 0,5 mm und der Schrumpf weniger als 2% beträgt; ferner sind keine Risse sichtbar; Kantenabheben, Schrumpf und / oder Rissbildung sind jedoch so stark ausgeprägt, dass ein Wert von „1“ nicht erzielt wurde;
• 3, dass das Kantenabheben weniger als 2,0 mm und der Schrumpf weniger als 5% beträgt; ferner sind maximal 2 Risse sichtbar; Kantenabheben, Schrumpf und / oder Rissbildung sind jedoch so stark ausgeprägt, dass ein Wert von „2“ nicht erzielt wurde;
• 4, dass das Kantenabheben weniger als 5,0 mm und der Schrumpf weniger als 10% beträgt; ferner sind maximal 5 Risse sichtbar; Kantenabheben, Schrumpf und / oder Rissbildung sind jedoch so stark ausgeprägt, dass ein Wert von „3“ nicht erzielt wurde;
• 5, dass sich das Etikett vollständig vom Untergrund ablöst („vollständiges Kantenabheben“) und der Schrumpf 10% oder mehr beträgt; ferner sind bis zu 10 Risse sichtbar;
• 6, dass sich das Etikett vollständig vom Untergrund ablöst („vollständiges Kantenabheben“) und der Schrumpf 10% oder mehr beträgt; ferner sind mehr als 10 Risse sichtbar.

The results are given as the average of five patterns and are ranked on a scale of 1 to 6. A value of

• 1 that the edge lift is less than 0.1 mm and the shrinkage is less than 0.5%; furthermore, no cracks are visible;
• 2 that the edge lift is less than 0.5 mm and the shrinkage is less than 2%; furthermore, no cracks are visible; However, edge lifting, shrinkage and / or cracking are so pronounced that a value of "1" was not achieved;
• 3 that the edge lift is less than 2.0 mm and the shrinkage is less than 5%; furthermore, a maximum of 2 cracks are visible; However, edge lifting, shrinkage and / or cracking are so pronounced that a value of "2" was not achieved;
• 4 that the edge lift is less than 5.0 mm and the shrinkage is less than 10%; furthermore, a maximum of 5 cracks are visible; However, edge lifting, shrinkage and / or cracking are so pronounced that a value of "3" was not achieved;
• 5 that the label peels completely from the substrate ("full edge lift") and the shrinkage is 10% or more; furthermore, up to 10 cracks are visible;
• 6 that the label is completely detached from the ground ("full edge lift") and the shrinkage is 10% or more; furthermore, more than 10 cracks are visible.

Tampering:

• 4, dass das Etikett zerstörungsfrei mit der Hand ohne zusätzliches Hilfsmittel abgelöst werden kann; die Manipulationssicherheit ist insofern ungenügend;
• 3, dass das Etikett nicht zerstörungsfrei mit der Hand aber mit Hilfe einer scharfen Metallklinge abgelöst werden kann; die Manipulationssicherheit ist insofern ebenfalls ungenügend;
• 2, dass das Etikett auch mit Hilfe einer scharfen Metallklinge als alleinigem zusätzlichem Hilfsmittel nicht zerstörungsfrei abgelöst werden kann; ein zerstörungsfreies Ablösen gelingt allerdings unter Verwendung von Isopropanol als Lösungsmittel in Kombination mit einer scharfen Metallklinge; die Manipulationssicherheit wird als ausreichend eingestuft;
• 1, dass das Etikett auch unter Verwendung von Isopropanol als Lösungsmittel in Kombination mit einer scharfen Metallklinge nicht zerstörungsfrei abgelöst werden kann; in diesem Fall wird die Manipulationssicherheit als gut eingestuft.

In the tamper evidence test, the brittleness of the sample after bubble-free bonding is examined on a 1 mm thick steel plate painted with a Clear Coat from Kansai Paint (KNIO 1210TW-2). To this end, it is attempted to remove the sample from the substrate after a waiting period of 24 hours after blister-free bonding to the steel plate. The tamper resistance of the laser label material is rated in four rating levels ("1" to "4"). It is checked with which aids the security label can be detached without destruction from the underground. In this context, "destruction" refers to breakage of the label and crack formation within the contrast layer. A value of

• 4 that the label can be detached non-destructively by hand without additional aids; the security against manipulation is insufficient;
• 3 that the label can not be detached nondestructively by hand, but with the help of a sharp metal blade; the security against manipulation is also insufficient;
• 2 that the label can not be removed without destroying even with the aid of a sharp metal blade as the sole additional aid; non-destructive peeling, however, succeeds when using isopropanol as solvent in combination with a sharp metal blade; the security against manipulation is classified as sufficient;
• 1, that the label can not be removed nondestructively even using isopropanol as a solvent in combination with a sharp metal blade; In this case, tamper resistance is rated as good.

Results

test method example 1 Example 2 temperature resistance 2 1 tampering 3 1

The pattern according to the invention (Example 2) shows an improved manipulation safety with improved long-term temperature resistance. Compared to this, the use of a conventional label with pressure-sensitive adhesive leads to inadequate resistance to tamper resistance (Example 1).

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 8130861 U1 [0003]
• DE 10048665 A1 [0003]
• DE 10142638 A1 [0003]
• DE 2011080803 A1 [0006]
• GB 25978 T [0039]

Cited non-patent literature

• DIN 53765-B-10 [0015]

Claims (11)

A laser-writable film comprising - a contrast layer based on a cured acrylate paint composition, wherein the cured acrylate paint composition is based on a composition comprising ◯ 30 to 80% by weight of a trifunctional oligomer A; ◯ 0 to 20% by weight of a trifunctional monomer B; ◯ 1 to 30% by weight of a difunctional monomer C; o and 2 to 40 wt .-% of a coloring pigment based; an engraving layer disposed above the contrast layer, characterized in that the film further comprises at least one adhesive layer disposed below the contrast layer, the adhesive layer being a latent-reactive adhesive layer comprising a thermoplastic component having a melting temperature T (melt) of 35 ° C ≤ T (melt) ≤ 90 ° C and contains functional groups which can react with isocyanate, and an isocyanate-containing component which particulate, in particular finely particulate, is dispersed in the thermoplastic component and blocked, microencapsulated or in the particle surface in the Is substantially deactivated, wherein the particles have a light-off temperature T (light off) of 40 ° C ≤ T (light off) ≤ 120 ° C, and wherein T (light-off) ≥ T (enamel) contains. Laser-writable film according to Claim 1 , characterized in that the trifunctional oligomer A is selected from the group of polyurethane tri (meth) acrylates and polyester tri (meth) acrylates. Laser inscribable film according to one of Claims 1 or 2 , characterized in that the trifunctional monomer B is selected from the group consisting of propoxylated and ethoxylated Glyceroltri (meth) acrylates of general formula I or mixtures thereof

wherein R in formula I is hydrogen or methyl; A is hydrogen or an ethyl group; X, Y and Z each independently represent a propylene or ethylene moiety; and a, b and c are each independently an integer from 1 to 4, and a + b + c represents a number between 3 and 12. Laser-inscribable film according to one of the preceding claims, characterized in that the difunctional monomer C is selected from the group of ethylene glycol diacrylates of the general formula (II)

and the propylene glycol diacrylates of the general formula (III)

or mixtures thereof, wherein n in the formulas (II) and (III) each independently represents an integer between 1 and 15. Laser-writable film according to one of the preceding claims, characterized in that the composition on which the acrylate paint composition is based, 50 to 60 wt .-% of the trifunctional oligomer A, 5 to 15 wt .-% of the trifunctional monomer B and 5 to 15 wt. -% of the difunctional monomer C includes. Laser inscribable film according to one of Claims 1 to 5 characterized in that the trifunctional oligomer A is an oligomer having three unsaturated (meth) acrylate units and a number average molecular weight, Mn, of from 1000 to 5000 g / mol; wherein the trifunctional monomer B is a monomer having three unsaturated (meth) acrylate units and a molecular weight of 300 to 1000 g / mol; and wherein the difunctional monomer C is a monomer having two unsaturated acrylate units per molecule and a molecular weight of 100 to 1000 g / mol. Laser inscribable film according to one of Claims 1 to 6 , characterized in that the light-off temperature of the particles T (light-off) ≤ 100 ° C, in particular ≤ 90 ° C, preferably ≥ 50 ° C, more preferably ≥ 60 ° C. Laser inscribable film according to one of Claims 1 to 7 , characterized in that for the melting temperature of the thermoplastic component T (melt) is: 40 ° C ≤ T (melt) ≤ 60 ° C. Laser inscribable film according to one of Claims 1 to 8th , characterized in that the film is in the form of a label. Use of the laser-writable film according to one of Claims 1 to 8th or the label after Claim 9 in the automotive industry. A process for producing a laser-writable film, comprising the following steps: i) providing a support film; ii) applying an engraving layer to the backing sheet; iii) applying an acrylate paint composition comprising ◯ 30 to 80% by weight of a trifunctional oligomer A; ◯ 0 to 20% by weight of a trifunctional monomer B; ◯ 1 to 30% by weight of a difunctional monomer C; ◯ and 2 to 40 wt .-% of a coloring pigment; iv) curing the acrylate paint composition to obtain a contrast layer; v) applying the latent-reactive adhesive layer comprising a thermoplastic component having a melting temperature T (melt) of 35 ° C ≤ T (melt) ≤ 90 ° C and containing functional groups capable of reacting with isocyanate and an isocyanate-containing component which is present particulate, in particular finely particulate, dispersed in the thermoplastic component and blocked, microencapsulated or substantially deactivated in the region of the particle surface, wherein the particles have a light-off temperature T (light off) of 40 ° C ≤ T (Anspring) ≤ 120 ° C. and wherein T (light-off) ≥ T (enamel) contains, on the contrast layer and the covering of the adhesive with a release paper or similar release liner; vi) and the removal of the support film.