RU2777533C1 - Labels to prevent falsification for variants of high temperature applications - Google Patents

Abstract

FIELD: counterfeit protection.

SUBSTANCE: invention relates to films made of poly(meth)acrylimide, and labels containing them to prevent falsification. Offered poly(meth)acrylimide film for use in the label to prevent falsification, containing, wt. %: poly(met)acrylimide containing at least 50 wt. % of the links of formula (I), where R¹ and R² are selected from hydrogen and methyl, and R³ is a hydrogen or C₁-C₄-alkyl group (30.0-92.5), one or more additives modifying impact strength (2.5-40.0), one or more inorganic fillers (5.0-40.0), if necessary, polyalkyl(meth)acrylate (0-30.0), one or more UV absorbers (0-5.0) and one or more UV stabilizers (0-5.0). The layered material for the manufacture of labels, a label, methods for their use and the use of labels to prevent falsification are also proposed.

EFFECT: provision of a brittle film for use in labels to prevent falsification with increased chemical resistance, which can be used at high temperatures.

14 cl, 3 dwg, 8 ex

Description

The field of technology to which the invention belongs

The present invention relates to poly(meth)acrylimide films for use in anti-counterfeit labels for high temperature applications, as well as anti-counterfeit labels containing these films. The films can advantageously be obtained by extrusion and, depending on the intended purpose, can be designed as transparent, translucent or completely opaque, for example, white. Theoretically, poly(meth)acrylimide films and anti-tampering labels containing such films do not have expected break points such as slits, perforations, etc.

The counterfeit prevention labels of the present invention are excellent in chemical resistance, high temperature resistance, and high weather stability. In particular, the labels show excellent chemical resistance in the presence of various chemicals commonly used in the automotive industry. For these reasons, the anti-tampering labels of the present invention can advantageously be used in an application where elevated temperatures of over 100° C. may occur without any sign of shrinkage in any dimension. Such applications include among others, labels for identifying electronic products, labels for electronic modules such as chip cards, electric motors and light-emitting devices that operate at elevated temperatures, various hidden car labels, road tax badges, document seals, product theft prevention labels and etc.

State of the art

Anti-counterfeiting labels, also known as security labels or anti-counterfeiting labels, are becoming increasingly important in the fight against counterfeiting. As a rule, the strength of their adhesion to the labeled substrate is high in comparison with the strength (flexural strength or tear strength) of the label itself. Therefore, theoretically, such labels cannot be peeled off from the marked product without destroying the label.

Anti-counterfeiting labels that cannot be removed without destruction are also used in various applications such as securing documents such as chip cards, passports, road tax IDs, anti-theft labels or price tags. A typical prior art chip card consists of no more than 12 separate parts, which are assembled and programmed in 30 separate processing steps. In such operations, a substrate layer, a layer containing a magnetic stripe, and separate laminates are applied for each function. Typically, one or more coats are required to provide sufficient weather protection, scratch protection, and UV protection. In the additional layer, a protective layer which cannot be removed without destroying it is applied to achieve anti-counterfeiting. Finally, the printed image is often applied to a separate outer layer, since it is difficult to apply a printed image to the other layers mentioned above.

Prior art labels for high temperature applications typically include an optional printable backing layer made of PET, PVC, PE, or BOPP. A second layer laminated to this layer using a pressure-sensitive adhesive on one face is required for weather stabilization. This second layer usually consists of polycarbonates, PET or PVC. Since layers of this type must be of limited brittleness, not least for improved handling, such labels must be further structured by notches or perforations to ensure that they cannot be removed without being destroyed. Unfortunately, the aforementioned materials tend to show signs of undesirable shrinkage at elevated temperatures for some time. In particular, extruded films often suffer from significant shrinkage in the machine direction, i.e. direction of extrusion. This behavior is particularly disadvantageous if the labels contain any machine-readable characters, such as barcodes, as shrinkage can make them unreadable.

Also known are anti-tampering labels made from films based on essentially pure PVC, in particular in the form of white films. These films have rather low tear strength. Unfortunately, however, PVC-based films have a relatively high tear resistance. This means that a PVC-based film can, under certain circumstances, be peeled off from the marked substrate by an unauthorized person with only a slight, almost imperceptible tear. In addition, PVC-based film has only limited thermal stability.

Because anti-counterfeit labels are extremely fragile, their production and handling on an industrial scale is much more difficult than conventional self-adhesive labels. For example, if a film, such as an acrylic film for use in anti-counterfeiting labels, is made by extrusion, the handling and use of such a film becomes problematic because it can easily break or tear.

To solve this problem, in US 6280835 it is proposed to obtain brittle acrylic films by coating a polyethylene terephthalate thin film used as a substrate with a coating, which is a liquid mixture, which is obtained by dissolving a thermoplastic acrylic resin in a suitable solvent and mixing obtained with an inorganic filler. In this way an extrusion step is avoided and the polyethylene terephthalate film gives the obtained multilayer material sufficient mechanical stability. In addition, solvent residues in the resulting film act as plasticizers, thereby making the film more flexible. However, such films have only limited thermal and chemical stability.

An additional common technical problem arises from the fact that labels are usually made from a label blank that contains a face layer (face material), an adhesive layer, for example, a pressure-sensitive adhesive (PSA) layer adhered to the face layer, optionally a release layer, and a backing layer removably adhered to the adhesive layer or release layer. The label blank is usually presented in the form of a roll. Individual labels are typically produced by punch cutting (notching) the face layer and the PSA layer and then removing the surrounding residual matrix, leaving individual labels adhered to the release liner. Because the facing material is extremely brittle, removing the residual matrix becomes extremely problematic as it can easily break or rupture.

Conventional label making processes are carried out at a speed of at least 25 m/min or even more. As speed increases, the process becomes less stable and the risk of fracture or rupture of the residual matrix upon removal increases. However, slowing down the process or increasing the width of the residual matrix web to allow better removal of the residual matrix will result in significant cost disadvantages, loss of efficiency, and can often be inefficient.

WO 2016/156137 A1 describes anti-tampering labels having high transparency and containing poly(meth)acrylate films. Such labels have good weather stability and are suitable for use in documents such as passports, anti-counterfeiting labels, road tax IDs, price tags, etc. The present inventors note that poly(meth)acrylate films exhibit the best characteristics if they contain no more than 10 wt. % impact modifier. Unfortunately, subsequent studies of the present inventors have shown that in some cases, in particular in the presence of a significant amount of inorganic fillers, such a low content of impact modifying additives can become problematic during the manufacture of such labels, if the method of manufacturing such labels includes the step notching (cutting by stamping). Under such circumstances, the excess matrix can sometimes break or rupture upon removal if the process is carried out at high speed. In addition, often such films have only limited thermal and chemical stability.

In principle, problems associated with fracture or rupture of the residual matrix could be at least partially reduced by increasing the distances between the individual labels, i.e. the width of the web of the residual matrix. However, this will inevitably increase the amount of waste generated during the manufacture of the label and reduce the efficiency of the process. Therefore, such an approach would not be acceptable from an economic and environmental point of view.

The published document WO 2019/042831 A1 describes brittle acrylic films made from impact-resistant polyalkyl (meth)acrylate and labels containing them to prevent counterfeiting. Films can advantageously be produced by extrusion and, depending on the desired purpose, can be designed to be translucent or completely opaque, eg white. Theoretically, fragile acrylic films and anti-tampering labels containing them do not contain predetermined break points such as slits, perforations, etc.

EP 3508323 A1 describes a multilayer film comprising a first acrylic resin layer (α1), an aromatic polycarbonate resin layer (β) and a second acrylic resin layer (α2). Acrylic resins constituting layer (α1) and layer (α2) may include among other things, poly(meth)acrylimide resin.

US 5,710,216 A describes films made from a thermoplastic molding material containing

a) from 1 to 98.5% by weight of partially aromatic copolyamide,

b) from 1 to 98.5% by weight of polymethacrylimide,

c) 0.5 to 30% by weight of the polycondensation product of aliphatic or aromatic polyhydric alcohols with epihalohydrins.

JP S59-025836 A describes a thermoplastic resin composition containing

(a) 5 to 95 parts by weight of polyamide and

(b) 95 to 5 parts by weight of polyglutarimide.

A task

In view of the prior art, the problem solved by the present invention was to provide a fragile film for use in labels to prevent adulteration with improved chemical resistance for high temperature applications. In particular, it is desirable that such a film be able to be used in a cost-effective manufacturing process in which individual labels are produced by notching the face layer and the PSA layer and then the surrounding residual matrix is removed, leaving individual labels adhered to the backing layer. Unlike existing extruded acrylic films, the required film should show virtually no signs of shrinkage at elevated temperatures.

More specifically, the object of the present invention was to provide a brittle, heat-resistant film for fabrication of anti-tampering labels that are characterized by low tear strength, low tear propagation resistance, and a short tear line to facilitate complete tearing of the film when attempted unauthorized removal, but, however, can be received and processed without interruption.

In a further aspect of the present invention, the object of providing self-adhesive, heat-resistant anti-counterfeiting labels that can be produced in a highly efficient manner, that are printable and suitable for long-term outdoor use is addressed.

Finally, the present invention solves the problem of providing a safe and cost-effective method for manufacturing the brittle heat-resistant film described above and anti-tampering self-adhesive labels containing it.

Solution

The present invention is based on the surprising discovery that high impact poly(meth)acrylimides, optionally in the presence of polyalkyl(meth)acrylate, can advantageously be used to make brittle heat resistant films with desired properties. Depending on the intended applications, the respective films can be designed as transparent, translucent or essentially opaque, for example, white. In particular, the inventors of the present invention have surprisingly found that the films exhibit suitable properties during the punch-cut (notch) process followed by removal of the residual matrix. Therefore, heat resistant anti-counterfeit labels containing the film of the present invention can advantageously be made by using a step where individual labels are obtained by notching and the surrounding residual matrix is then removed, leaving individual labels adhered to the release liner. Unwanted breakage of the residual matrix does not occur even at operating speeds of at least 25 m/min or even higher.

Unlike the prior art polyalkyl(meth)acrylate, the poly(meth)acrylimide film of the present invention typically contains less than 5.0 wt. %, more preferably less than 2.0 wt. %, even more preferably less than 1.0 wt. %, in particular less than 1.0 wt. % aromatic or aliphatic polyamides, based on the weight of the poly(meth)acrylimide film.

A person skilled in the art will understand that the composition of the film according to the present invention, indicated below, is the composition of the sand from which at least one layer of film is made.

One aspect of the present invention relates to a poly(meth)acrylimide film for use in a counterfeit prevention label, wherein the poly(meth)acrylimide film comprises

from 30.0 wt. % up to 98.0 wt. % poly(meth)acrylimide;

from 2.0 wt. % up to 50.0 wt. % of one or more impact modifiers;

from 0.0 wt. % up to 30.0 wt. % polyalkyl(meth)acrylate;

from 0.0 wt. % up to 40.0 wt. % of one or more inorganic fillers;

from 0.0 wt. % up to 5.0 wt. % of one or more UV absorbers and

from 0.0 wt. % up to 5.0 wt. % of one or more UV stabilizers, based on the weight of the poly(meth)acrylimide film;

where poly(meth)acrylimide contains at least 50 wt. %, preferably at least 60 wt. %, most preferably at least 70 wt. % based on the weight of poly(meth)acrylimide repeating units of formula (I),

wherein R ¹ and R ² are independently selected from hydrogen and a methyl group, preferably R ¹ and R ² are a methyl group, and

R ³ is hydrogen or a C ₁ -C ₄ alkyl group, preferably a methyl group; and

while the total content of poly(meth)acrylimide, polyalkyl(meth)acrylate and an additive that modifies impact strength is from 75.0 wt. % to 100.0 wt. %, preferably from 85.0 wt. % to 100.0 wt. %, more preferably from 95.0 wt. % to 100.0 wt. % based on the weight of the poly(meth)acrylimide film.

A further aspect of the present invention relates to a poly(meth)acrylimide film for use in a counterfeit prevention label, wherein the poly(meth)acrylimide film comprises

from 30.0 wt. % to 92.5 wt. % poly(meth)acrylimide;

from 2.5 wt. % up to 40.0 wt. % of one or more impact modifiers;

from 0.0 wt. % up to 30.0 wt. % polyalkyl(meth)acrylate;

from 5.0 wt. % up to 40.0 wt. % of one or more inorganic fillers;

from 0.0 wt. % up to 5.0 wt. % of one or more UV absorbers and

from 0.0 wt. % up to 5.0 wt. % of one or more UV stabilizers, based on the weight of the poly(meth)acrylimide film;

where poly(meth)acrylimide contains at least 50 wt. %, preferably at least 60 wt. %, most preferably at least 70 wt. % based on the weight of poly(meth)acrylimide repeating units of formula (I),

wherein R ¹ and R ² are independently selected from hydrogen and a methyl group, preferably R ¹ and R ² are a methyl group, and

R ³ is hydrogen or a C ₁ -C ₄ alkyl group, preferably a methyl group; and

while the total content of poly(meth)acrylimide, polyalkyl(meth)acrylate and an additive that modifies impact strength is from 60.0 wt. % up to 95.0 wt. %, preferably from 70.0 wt. % up to 95.0 wt. %, even more preferably from 80.0 wt. % up to 95.0 wt. % based on the weight of the poly(meth)acrylimide film; and wherein

content in weight. The % of one or more impact modifiers, n _im , in a poly(meth)acrylimide film is described by the following relationship:

0.5 × n _f < n _im < 1.8 × n _f ,

wherein n _f is the content in weight. % of one or more inorganic fillers in the poly(meth)acrylimide film.

A further aspect of the present invention relates to a counterfeit prevention label comprising the poly(meth)acrylimide film described above.

In another additional aspect, the present invention relates to a laminate for the manufacture of the specified label to prevent counterfeiting, while the laminate contains at least the following layers:

a) a backing layer, preferably having a tear resistance of 50 N to 500 N, measured in accordance with ASTM D1004 (2013) using a 50.0 µm thin film; and

b) a layer consisting of a poly(meth)acrylimide film.

Another additional aspect of the present invention relates to a method for manufacturing a laminate, the method comprising at least the following steps i) and ii):

i) obtaining said poly(meth)acrylimide film using an extruder, whereby a poly(meth)acrylimide film is obtained; and

ii) bonding the backing layer to the poly(meth)acrylimide film from step i) downstream of the extruder.

Another additional aspect of the present invention relates to a method for manufacturing a counterfeit prevention label, the method comprising at least the following steps i) to iv):

i) obtaining a poly(meth)acrylimide film using an extruder;

ii) bonding the backing layer to the poly(meth)acrylimide film from step i) downstream of the extruder to form a laminate;

iii) bonding an adhesive layer, optionally a release layer and a backing layer to the laminate from step ii), whereby a label blank is obtained; and

iv) notching the label blank obtained in step iii) and removing the resulting residual matrix, thereby obtaining a plurality of individual self-adhesive labels to prevent falsification on the substrate layer.

Finally, the present invention relates to the use of a counterfeit prevention label for the manufacture of chip cards, documents, counterfeit prevention labels, electronic product identification labels, various concealed automotive labels, document seals or price tags.

Brief description of graphic materials

Fig. 1. Schematic representation of a continuous blank 1 for labels after the notching method. In a subsequent process step, the residual matrix 3 is removed from the backing layer, leaving behind a plurality of individual anti-counterfeiting labels 2 attached to the backing layer.

Fig. 2. Side view of a counterfeit prevention label laminate 4 comprising a backing layer 5 and a layer consisting of a poly(meth)acrylimide film 6 '.

Fig. 3. Side view of an anti-tampering label 2 containing at least the following layers:

a) a layer consisting of a poly(meth)acrylimide film 6 ;

b) adhesive layer 7 ;

c) optionally a separating layer 8 and

d) backing layer 9 .

Detailed description of the invention

The poly(meth)acrylimide film of the present invention has the following composition:

from 30.0 wt. % up to 98.0 wt. % poly(meth)acrylimide;

from 2.0 wt. % up to 50.0 wt. % of one or more impact modifiers;

from 0.0 wt. % up to 30.0 wt. % polyalkyl(meth)acrylate;

from 0.0 wt. % up to 40.0 wt. % of one or more inorganic fillers;

from 0.0 wt. % up to 5.0 wt. % of one or more UV absorbers and

from 0.0 wt. % up to 5.0 wt. % of one or more UV stabilizers, based on the weight of the poly(meth)acrylimide film.

Poly(meth)acrylimide contains at least 50 wt. %, preferably at least 60 wt. %, most preferably at least 70 wt. % based on the weight of poly(meth)acrylimide repeating units of formula (I),

wherein R ¹ and R ² are independently selected from hydrogen and a methyl group, preferably R ¹ and R ² are a methyl group, and

R ³ is hydrogen or a C ₁ -C ₄ alkyl group, preferably a methyl group.

The total content of poly(meth)acrylimide, polyalkyl(meth)acrylate and impact strength modifying additive is from 75.0 wt. % to 100.0 wt. %, preferably from 85.0 wt. % to 100.0 wt. %, more preferably from 95.0 wt. % to 100.0 wt. % based on the weight of the poly(meth)acrylimide film.

As will be understood by a person skilled in the art, the quantities

• poly(meth)acrylimide;

• one or more impact modifiers;

• polyalkyl(meth)acrylate;

• one or more inorganic fillers;

• one or more UV absorbers and

• one or more UV stabilizers, based on the weight of the poly(meth)acrylimide film

in the amount of not more than 100 wt. %.

The film of the present invention can be designed to be substantially transparent if desired. The term " substantially transparent " as used herein refers to a material having a transmission (D65) of at least 50%, preferably at least 60%, more preferably at least 70%, even more preferably at least 80% and particularly preferably at least 90%, as defined for a sample with a thickness of 50.0 μm in accordance with the normative document ISO 13468-2 (2006).

In a further important embodiment of the present invention, the brittle heat resistant film is substantially opaque and contains at least one inorganic filler. While examining these films, the inventors of the present invention surprisingly found that their behavior during the punching (notching) process followed by removal of the residual matrix strongly depends on the ratio of the impact modifier and the amount of inorganic filler in the film. In particular, the authors of the present invention have found that poly(meth)acrylimide films, in which the total content of one or more impact modifying additives, n _im , expressed in weight. % in terms of the total weight of the film, is described by the following dependence:

0.5 × n _f < n _im < 1.8 × n _f ,

and n _f is the total content of one or more inorganic fillers, expressed in weight. % based on the total weight of the film,

are particularly suitable for processing with the notching method. Therefore, anti-counterfeit labels containing the film of the present invention can advantageously be made by using a step where individual labels are obtained by scoring and the surrounding residual matrix is then removed, leaving individual labels adhered to the release liner. Unwanted breakage of the residual matrix does not occur even at operating speeds of at least 25 m/min or even higher.

In this application, the content of one or more impact modifiers, n _im , is the content of pure impact modifiers. In the case of particulate impact modifiers, n _im is the pure particulate content of the impact modifier. Therefore, if the respective impact modifying additives are rubber particles, then n _im represents the content of rubber particles in the poly(meth)acrylimide film. If the respective impact modifiers are core-sheath, core-sheath-sheath, or core-sheath-sheath-sheath particles, then n _im is the total particle content of the poly(meth)acrylimide film.

Therefore, one embodiment of the present invention relates to a poly(meth)acrylimide film containing

from 30.0 wt. % to 92.5 wt. % poly(meth)acrylimide;

from 2.5 wt. % up to 40.0 wt. % of one or more impact modifiers;

from 0.0 wt. % up to 30.0 wt. % polyalkyl(meth)acrylate;

from 5.0 wt. % up to 40.0 wt. % of one or more inorganic fillers;

from 0.0 wt. % up to 5.0 wt. % of one or more UV absorbers and

from 0.0 wt. % up to 5.0 wt. % of one or more UV stabilizers, based on the weight of the poly(meth)acrylimide film;

where the total content of poly(meth)acrylimide, polyalkyl(meth)acrylate and impact strength modifying additive is from 75.0 wt. % up to 95.0 wt. %, preferably from 85.0 wt. % to 100.0 wt. %, more preferably from 95.0 wt. % to 100.0 wt. % based on the weight of the poly(meth)acrylimide film; and wherein

content in weight. The % of one or more impact modifiers, n _im , in a poly(meth)acrylimide film is described by the following relationship:

0.5 × n _f < n _im < 1.8 × n _f ,

preferably 0.55 × n _f < n _im < 1.6 × n _f ,

more preferably 0.6 x n _f < n _im < 1.5 x n _f ,

wherein n _f is the content in weight. % of one or more inorganic fillers in the poly(meth)acrylimide film.

In addition, the inventors of the present invention have found that the balance between, on the one hand, suitability for a manufacturing method including a notching step followed by removal of the residual matrix, and, on the other hand, the ability to prevent an unauthorized attempt to peel a label to prevent falsification from a given substrate, is particularly advantageous, if the poly(meth)acrylimide film contains

from 40.0 wt. % to 80.0 wt. % poly(meth)acrylimide;

from 4.0 wt. % up to 35.0 wt. % of one or more impact modifiers;

from 0.0 wt. % up to 25.0 wt. % polyalkyl(meth)acrylate;

from 8.0 wt. % up to 35.0 wt. % of one or more inorganic fillers;

from 0.0 wt. % up to 5.0 wt. % of one or more UV absorbers and

from 0.0 wt. % up to 5.0 wt. % of one or more UV stabilizers, based on the weight of the poly(meth)acrylimide film;

while the total content of poly(meth)acrylimide, polyalkyl(meth)acrylate and additives that modify the impact strength is from 65.0 wt. % to 92.0 wt. % based on the weight of the poly(meth)acrylimide film; and at the same time the content of one or more additives that modify impact strength, n _im per weight. % in poly(meth)acrylimide film is described by the following dependence:

0.5 × n _f < n _im < 1.8 × n _f ,

preferably 0.55 × n _f < n _im < 1.6 × n _f ,

more preferably 0.6 x n _f < n _im < 1.5 x n _f ,

wherein n _f is the content in weight. % of one or more inorganic fillers in the poly(meth)acrylimide film.

In addition, the present inventors have found that the overall properties of the poly(meth)acrylimide film can be further improved if the poly(meth)acrylimide film contains

from 45.0 wt. % up to 75.0 wt. % poly(meth)acrylimide;

from 6.0 wt. % up to 30.0 wt. % of one or more impact modifiers;

from 0.0 wt. % to 20.0 wt. % polyalkyl(meth)acrylate;

from 10.0 wt. % up to 30.0 wt. % of one or more inorganic fillers;

from 0.0 wt. % up to 5.0 wt. % of one or more UV absorbers and

from 0.0 wt. % up to 5.0 wt. % of one or more UV stabilizers, based on the weight of the poly(meth)acrylimide film;

while the total content of poly(meth)acrylimide, polyalkyl(meth)acrylate and additives that modify the impact strength is from 70.0 wt. % up to 90.0 wt. % based on the weight of the poly(meth)acrylimide film; and at the same time the content of one or more additives that modify impact strength, n _im per weight. % in poly(meth)acrylimide film is described by the following dependence:

0.5 × n _f < n _im < 1.8 × n _f ,

preferably 0.55 × n _f < n _im < 1.6 × n _f ,

more preferably 0.6 x n _f < n _im < 1.5 x n _f ,

wherein n _f is the content in weight. % of one or more inorganic fillers in the poly(meth)acrylimide film.

Poly(meth)acrylimide film

Typically, the poly(meth)acrylimide film of the present invention consists of one single layer, i.e. it is a monolayer film. Such films can be made using methods known to the person skilled in the art, such as solution coating, casting or extrusion, where extrusion is particularly preferred in terms of high productivity and advantageous properties of the resulting film. Surprisingly, although the poly(meth)acrylimide film of the present invention is extremely brittle, the film can be conveniently made by extrusion and then, for example, store for shipment to the consumer or immediately use for the manufacture of labels to prevent falsification.

In order to optimally provide the required purpose, the poly(meth)acrylimide film of the present invention is characterized by a tensile stress of 20.0 MPa to 70.0 MPa, measured in accordance with DIN EN ISO 527-3/2/100 (2003) using a thin film 50.0 µm thick. Although a film having a tensile stress of less than 20.0 MPa will still be suitable for use in accordance with the present invention, great care will be required during its manufacture and handling, since the film can break easily.

On the other hand, although the poly(meth)acrylimide film of the present invention, having a tensile stress of more than 70.0 MPa, is highly suitable for a method for manufacturing counterfeit prevention labels, the use of such labels may carry an increased risk that such The label can be removed with a thin, sharp blade (e.g. razor blade) from the initially marked substrate and subsequently reattached to another substrate.

In terms of providing a good balance between ease of handling and film fragility, the tear resistance is typically in the range of 1.0 N to 15.0 N. The tensile stress of a poly(meth)acrylimide film can be determined by a conventional method known to the skilled person, such as the method described in DIN EN ISO 527-3/2/100 (2003) and is usually measured in the direction of extrusion.

Preferably, the poly(meth)acrylimide film has a tear resistance measured according to ASTM D1938 (2014) using a 50.0 µm thin film of 0.01 N/mm to 1.50 N/mm, preferably from 0.1 N/mm to 1.20 N/mm. Tear resistance is usually measured in the direction of extrusion.

In addition, to provide an optimal balance between the processability of the poly(meth)acrylimide film and the ability of the final labels to resist tampering, it is preferred that the poly(meth)acrylimide film have an elongation at break in the range of 3.0 % to 30%, measured according to DIN EN ISO 527-3/2/100 (2003) using a thin film of 50.0 µm, with an elongation at break ranging from 8.0% to 25.0 % is particularly advantageous from a handling point of view.

If the elongation at break is less than 3.0%, the elasticity of the film is too low, so that the handling of the film becomes difficult, and great care must be taken during manufacturing to prevent damage to the film. Under such circumstances, it may be necessary to carry out the manufacturing process at a lower speed. On the other hand, if the elongation at break exceeds 30.0%, then the brittleness of the film generally decreases. Therefore, when attempting to remove the anti-tampering label with a thin, sharp blade, slight mechanical deformation of the film (i.e. less than 25%) may not necessarily lead to its complete rupture. This increases the risk that a skilled and experienced person using a tool that is thin and sharp enough to successfully remove an anti-tampering label from the original substrate (e.g. from a vehicle engine replacement part) to reattach it to another object (non-Genuine replacement part). The elongation at break of a poly(meth)acrylimide film can be measured by a conventional method known to the skilled person, for example as described in DIN EN ISO 527-3/2/100 (2003).

In accordance with the present invention, there are also various influencing factors, which, being varied, allow the person skilled in the art to adjust the elongation at break of the film of the present invention in the desired direction.

The main influencing factors are the amounts of impact modifiers and inorganic fillers. More specifically, increasing the concentration of impact modifiers also increases elongation at break, and thus lower amounts of impact modifiers affect the low elongation at break of the present invention.

In one preferred embodiment, the tear resistance of the poly(meth)acrylimide film is at least 10 times greater, preferably at least 50 times greater, even more preferably at least 100 times greater than the tear propagation resistance. This is particularly advantageous and ensures that even slight tearing of the film, which occurs when an unauthorized attempt is made to remove the label to prevent counterfeiting from the substrate, quickly propagates throughout the entire label and leads to the complete destruction of the label. This further reduces the risk of unauthorized label removal.

Advantageously, the dimensional stability of the extruded film of the present invention at 120° C. (30 minutes) is at most 0.7%, preferably at most 0.5% in the machine direction (extrusion direction) and at most 0.5%, preferably at most 0.3% in the transverse direction (direction perpendicular to the machine direction). If the film of the present invention is produced by a method other than extrusion, its dimensional stability is not more than 0.5%, preferably not more than 0.3%.

Dimensional stability can be measured in accordance with DIN EN ISO 11501 (2004) using 50.0 µm foil. Measurements can be made at 120 C for a period of 30 minutes.

In addition, the film of the present invention has excellent chemical resistance in the presence of common chemicals such as disinfectants, detergents, and various liquids commonly used in road vehicles, such as hydraulic fluid, brake fluid, engine oil, etc. For this reason, the films are particularly suitable for under-the-hood labeling applications.

The thickness of the poly(meth)acrylimide film of the present invention is preferably in the range of 15.0 µm to 120.0 µm. If the thickness is less than 15.0 µm, great care must be taken during the manufacture and handling of the film to prevent tearing. On the other hand, if the film thickness exceeds 120.0 µm, its mechanical stability is quite high, and this, again, increases the risk that the film does not break when an unauthorized label is removed. In addition, a large thickness of the film will result in a high thickness of the anti-tampering label containing it, which may be disadvantageous from an aesthetic point of view or for other reasons. In order to provide a proper balance between ease of handling and flatness, the thickness of the poly(meth)acrylimide film is preferably in the range of 30.0 µm to 90.0 µm, with the range of 40.0 µm to 75.0 µm being even more preferred.

The thickness of the film of the present invention can be determined by mechanical scanning in accordance with the normative document ISO 4593 (1993). However, preferably the film thickness of the present invention is determined using micrographs obtained using a scanning electron microscope such as JEOL JSM-IT300 (commercially available from JEOL GmbH, Freising, Germany). For this purpose, film samples can be frozen in liquid nitrogen, mechanically crushed, and freshly obtained surfaces analyzed. For example, the measurement can be performed using the following parameters.

Poly(meth)acrylimides

The poly(meth)acrylimide (PMMI) used in the present invention contains at least 50 wt. %, preferably at least 60 wt. %, most preferably at least 70 wt. % based on the weight of poly(meth)acrylimide repeating units of formula (I),

wherein R ¹ and R ² are independently selected from hydrogen and a methyl group, preferably R ¹ and R ² are a methyl group, and

R ³ is hydrogen or a C ₁ -C ₄ alkyl group, preferably a methyl group.

Methods for producing PMMI are, by way of example, disclosed in EP-A 216505, EP-A 666161 or EP-A 776910, the full disclosure of which is incorporated herein by reference.

The starting material used for the production of PMMI comprises a polymer derived from methacrylic acid alkyl esters and is usually composed of more than 50.0% by weight, preferably more than 80.0% by weight, particularly preferably from 95.0% by weight to 100, 0% by weight of units of methacrylic acid alkyl esters containing from 1 to 4 carbon atoms in the alkyl radical. Preferred is methyl methacrylate. Preferred polymers consist of at least 80.0% by weight, preferably more than 90.0% by weight, particularly preferably more than 95.0% by weight of methyl methacrylate. Comonomers that can be used include any of the monomers capable of copolymerization with methyl methacrylate, in particular alkyl esters of acrylic acid having from 1 to 4 carbon atoms in the alkyl radical, acrylo- or methacrylonitrile, acryl- or methacrylamide, styrene or maleic anhydride . Preference is given to polymers of this type suitable for thermoplastic processing, the reduced viscosity of which is in the range from 20 ml/g to 92 ml/g, preferably from 50 ml/g to 80 ml/g (measured in accordance with ISO 8257 (2006), part 2). They are used in the form of powder or granules, the average particle size of which is from about 0.03 mm to 3 mm.

It is important that, in the process step, ammonia is first used as an imitation agent, and that a C _1-4 -alkylamine, usually methylamine, is used in the subsequent process step, and that the molar ratio of ammonia to methylamine used is from 1:0.5 to 1: 3, preferably 1:0.8 to 1:2.7, particularly preferably 1:0.9 to 1:1.1. Below this range, increased haze may occur in the resulting polymethacrylimide. If there is a molar excess of methylamine, based on the ammonia used, the proportion of carboxylic acid groups in the polymer, in turn, undesirably increases.

The reaction with the imidizing agent is stopped before the polymer is fully imidated. For this purpose, the total amount of imidating agents used may, for example, be from 0.2 to 2.5 moles, preferably from 0.5 to 1.5 moles, particularly preferably from 0.8 to 1.2 moles, per base moles of ester units. . However, it is always necessary to maintain a certain quantitative ratio of ammonia and methylamine. In this case, this provides polymers that consist of approximately 20-80 base mol. % cyclic methacrylimide units and contain only small amounts of less than 5.0% by weight of methacrylic acid units.

The imidation process can be carried out essentially by a known method per se , for example as described in EP 441148. The imidation is best performed at temperatures above the melting point or at least 20° C. above the Vicat softening point B according to ISO 306 (2014) for original polymer. More preferably, the reaction temperature is chosen to be at least 20° C. higher than the softening temperature of the resulting imidated polymer. Since the Vicat softening temperature of the imidated polymer is usually the target process variable and the degree of imidation to be achieved is determined accordingly, it is also easy to determine the required minimum temperature. The temperature range from 140°C to 300°C is preferred, in particular from 150°C to 260°C, particularly preferably from 180°C to 220°C. Excessively high reaction temperatures sometimes lead to a decrease in viscosity caused to some extent by termination of the polymer chain. To avoid subjecting the polymer to unnecessary thermal stress, the reaction temperature may, for example, be raised gradually or in stages, starting from a temperature slightly above the melting point of the starting polymer, and only at the final stage, the temperature exceeds the softening temperature of the imidated final product by at least 20°C. The reaction steps are preferably operated at autogenous pressure, which can range from 50 to 500 bar. The pressure reduction can be carried out at different stages of the process, for example, to remove volatile substances. In this case, the temperature of the reaction mixture may fall, and it must be raised again to the required value. If the imitation agent is introduced under the reaction conditions, in this case, of course, a correspondingly high pressure must be applied.

Partial or complete imidation of methacrylic acid alkyl ester polymers by reaction with an imidizing agent, such as a primary amine, is disclosed as an example in US 2146209. The polymer is heated to temperatures from 140°C to 250°C in the presence or absence of a solvent with an means, if necessary, under pressure.

Typically, PMMIs for use in the present invention are characterized by a weight average molar mass Mw of 80,000 g/mol to 200,000 g/mol, preferably 90,000 g/mol to 150,000 g/mol, determined by GPC using PMMA as a standard. Such materials are commercially available from Evonik Performance Materials GmbH (Darmstadt, Germany) under the trademark PLEXIMID®. Suitable products include, without limitation, PLEXIMID® TT50, PLEXIMID® TT70, PLEXIMID® 8805, PLEXIMID® 8813, PLEXIMID® 8817.

The film of the present invention typically contains from 30.0 wt. % up to 98.0 wt. %, preferably from 30.0 wt. % to 92.5 wt. %, more preferably from 40.0 wt. % to 80.0 wt. %, even more preferably from 45.0 wt. % up to 75.0 wt. %, based on the weight of the poly(meth)acrylimide film.

Polyalkyl(meth)acrylates

The poly(meth)acrylimide film of the present invention may contain from 0.0 wt. % up to 30.0 wt. % polyalkyl(meth)acrylate, based on the weight of the poly(meth)acrylimide film.

Polyalkyl (meth)acrylates are usually obtained by free radical polymerization of mixtures that usually contain alkyl (meth)acrylate, usually methyl methacrylate (a), and at least one additional (meth)acrylate (b). Such mixtures usually contain at least 50 wt. %, preferably at least 60 wt. %, particularly preferably at least 80 wt. % and even more preferably at least 90 wt. % methyl methacrylate (a) based on the weight of the monomers. A commonly used amount of methyl methacrylate (a) is from 50.0 wt. % up to 99.9 wt. %, preferably from 80.0 wt. % to 99.0 wt. % and particularly preferably from 90.0 wt. % to 99.0 wt. % based on the weight of the monomers.

Such mixtures for the preparation of polyalkyl(meth)acrylates may also contain other (meth)acrylates (b) capable of copolymerization with methyl methacrylate (a). As used in this document, the term "(meth)acrylate» covers methacrylates, acrylates and mixtures thereof. (Meth)acrylates can be formed from saturated alcohols, for example, methyl acrylate, ethyl (meth) acrylate, propyl (meth) acrylate,n-butyl(meth)acrylate,tert-butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate and 2-ethylhexyl (meth) acrylate; or from unsaturated alcohols, for example, allyl(meth)acrylate, vinyl(meth)acrylic; as well as aryl(meth)acrylates such as benzyl(meth)acrylate or phenyl(meth)acrylate, cycloalkyl(meth)acrylates such as 3-vinylcyclohexyl(meth)acrylate, bornyl(meth)acrylate; hydroxyalkyl(meth)acrylates such as 3-hydroxypropyl(meth)acrylate, 3,4-dihydroxybutyl(meth)acrylate, 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate; glycol di(meth)acrylates such as 1,4-butanediol(meth)acrylate; amides and nitrites of (meth)acrylic acid, for example,N-(3-dimethylaminopropyl)(meth)acrylamide,N-(diethylphosphono)-(meth)acrylamide, 1-methacryloylamido-2-methyl-2-propanol; polyfunctional (meth)acrylates such as trimethyloylpropane-tri(meth)acrylate.

A commonly used amount of (meth)acrylic comonomers (b) is from 0.1 wt. % up to 50.0 wt. %, preferably from 1.0 wt. % to 20.0 wt. % and particularly preferably from 1.0 wt. % to 10.0 wt. %, based on the weight of the monomers, and the compounds in this case can be used individually or in the form of a mixture.

The polymerization reaction is usually initiated by known free radical polymerization initiators. Preferred initiators include among others, azo initiators well known to those skilled in the art, for example, AIBN and 1,1-azobiscyclohexanecarbonitrile, and peroxy compounds such as methyl ethyl ketone peroxide, acetylacetone peroxide, dilauryl peroxide,tert-butyl 2-ethyl perhexanoate, ketone peroxide, methyl isobutyl ketone peroxide, cyclohexanone peroxide, dibenzoyl peroxide,tert-butyl peroxybenzoate,tert-butylperoxyisopropyl carbonate, 2,5-bis(2-ethylhexanoylperoxy)-2,5-dimethylhexane,tert-butyl-2-ethylperoxyhexanoate,tert-butyl 3,5,5-trimethylperoxyhexanoate, dicumyl peroxide, 1,1-bis(tert-butylperoxy)cyclohexane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, cumyl hydroperoxide,tert-butyl hydroperoxide, bis(4-tert-butylcyclohexyl)peroxydicarbonate, mixtures of two or more of the above compounds with each other, and mixtures of the above compounds with compounds which have not been listed but which can similarly form free radicals.

The compositions to be polymerized may contain not only methyl methacrylate (a) and (meth)acrylates (b) described above, but also other unsaturated monomers which are copolymerizable with methyl methacrylate and with the above (meth)acrylates. Among these are inter alia 1-alkenes such as 1-hexene, 1-heptene; branched alkenes such as vinylcyclohexane, 3,3-dimethyl-1-propene, 3-methyl-1-diisobutylene, 4-methyl-1-pentene, norbornene; acrylonitrile; vinyl esters such as vinyl acetate; styrene, substituted styrenes with an alkyl substituent in the side chain, for example, α-methylstyrene and α-ethylstyrene, substituted styrenes with an alkyl substituent on the ring, such as vinyltoluene andP-methylstyrene, halogenated styrenes such as monochlorostyrenes, dichlorostyrenes, tribromostyrenes and tetrabromostyrenes; vinyl ethers and isoprenyl ethers; maleic acid derivatives such as maleic anhydride, methylmaleic anhydride, maleimide, methylmaleimide; and dienes such as divinylbenzene.

A commonly used amount of such comonomers (c) is from 0.0 wt. % to 20.0 wt. %, preferably from 0.0 wt. % to 15.0 wt. % and particularly preferably from 0.0 wt. % to 10.0 wt. %, based on the weight of the monomers, and the compounds in this case can be used individually or in the form of a mixture.

More preference is given to polyalkyl(meth)acrylates, which are obtained by polymerization of a composition containing as polymerizable constituents:

(a) from 50.0 wt. % up to 99.9 wt. % methyl methacrylate,

(b) from 0.1 wt. % up to 50.0 wt. % acrylic acid ester and C1-C4 alcohol,

(c) from 0.0 wt. % to 10.0 wt. % of monomers capable of copolymerization with monomers (a) and (b).

In another additional embodiment, preference is given to polyalkyl (meth)acrylates, consisting of methyl methacrylate in an amount of from 85.0 wt. % up to 99.5 wt. % and methyl acrylate in an amount of 0.5 wt. % to 15.0 wt. %, while the amounts in this case are given in terms of 100 wt. % polymerizable components. Particularly advantageous copolymers are those obtained by copolymerization from 90.0 wt. % up to 99.5 wt. % methyl methacrylate and from 0.5 wt. % to 10.0 wt. % methyl acrylate, where amounts are given in terms of 100 wt. % polymerizable components. For example, polyalkyl(meth)acrylates may contain 91.0 wt. % methyl methacrylate and 9.0 wt. % methyl acrylate, 96.0 wt. % methyl methacrylate and 4.0 wt. % methyl acrylate or 99.0 wt. % methyl methacrylate and 1.0 wt. % methyl acrylate. The Vicat softening point VSP (ISO 306 (2013), method B50) of said polyalkyl(meth)acrylates is generally at least 90°C, preferably between 95°C and 112°C.

The weight average molar mass Mw of polyalkyl(meth)acrylates typically ranges from 80,000 g/mol to 300,000 g/mol. Particularly advantageous mechanical properties are obtained for thin films with polyalkyl(meth)acrylates having an average molar mass Mw in the range of 80,000 g/mol to 200,000 g/mol, preferably in the range of 100,000 g/mol to 180,000 g/mol, more preferably in range from 120,000 g/mol to 180,000 g/mol, determined in each case by GPC against PMMA calibration standards and THF as eluent.

Suitable polyalkyl(meth)acrylates for use in the films of the present invention are commercially available from Evonik Performance Materials GmbH (Darmstadt, Germany) under the trademark PLEXIGLAS®. Such products include, without limitation, PLEXIGLAS® 7N, PLEXIGLAS® 7H, PLEXIGLAS® 8N, PLEXIGLAS® 8H, and PLEXIGLAS® Heatresist FT15.

The film of the present invention typically contains from 0.0 wt. % up to 30.0 wt. %, preferably from 0.0 wt. % up to 25.0 wt. %, more preferably from 0.0 wt. % to 20.0 wt. % polyalkyl(meth)acrylate, based on the weight of the poly(meth)acrylimide film.

Impact Modifying Additives

Impact modifiers for use in the present invention are well known.per se and can be characterized by different chemical compositions and different structures of the polymer. Impact modifiers may be cross-linked or thermoplastic. In addition, the impact strength modifying additives may be in particulate form such as core-shell, core-shell-shell, or core-shell-shell-shell particles. Generally, particulate impact modifiers have an average particle diameter of 20 mm to 500 nm, preferably 50 mm to 450 nm, more preferably 100 mm to 400 nm, and most preferably 150 mm to 350 nm. "Particles" in this context means cross-linked impact strength modifying additives, which typically have a core-shell, core-shell-shell, or core-shell-shell structure. The average particle diameter can be determined using a method known to a person skilled in the art, for example, using photon correlation spectroscopy in accordance with DIN ISO 13321:(1996).

In its simplest form, particulate impact modifiers are cross-linked particles obtained by emulsion polymerization, with an average particle diameter in the range of 10 nm to 150 nm, preferably 20 nm to 100 nm, in particular from 30 nm to 90 nm. They usually consist of butyl acrylate in an amount of at least 20.0 wt. %, preferably from 20.0 wt. % to 99.0 wt. %, particularly preferably in the range of 30.0 wt. % to 98.0 wt. % and a cross-linking monomer in an amount of 0.1 wt. % to 2.0 wt. %, preferably from 0.5 wt. % to 1.0 wt. %, e.g. polyfunctional (meth)acrylate, for example, allyl methacrylate, and, if necessary, other monomers, e.g. C_one-C_fouralkyl methacrylates in an amount of 0.0 wt. % to 10.0 wt. %, preferably from 0.5 wt. % up to 5.0 wt. %, such as ethyl acrylate or butyl methacrylate, preferably methyl acrylate, or other vinyl polymerizable monomers, such as styrene.

Preferred impact modifiers are polymer particles, which may have a two- or three-layer core-shell structure and are obtained by emulsion polymerization (see, for example, EP-A 0113924, EP-A 0522351, EP-A 0465049 and EP -A 0683028). The films of the present invention generally require a suitable average particle diameter of such emulsion polymers in the range of 20 nm to 500 nm, preferably 50 nm to 450 nm, more preferably 100 nm to 400 nm, and most preferably 150 nm to 350 nm.

A three-layer or three-phase structure with a core and two shells can be obtained as follows. The innermost (hard) shell may, for example, consist essentially of methyl methacrylate, small proportions of comonomers, for example, ethyl acrylate, and a proportion of a cross-linking agent, for example, allyl methacrylate. The middle (soft) shell may, for example, consist of a copolymer containing butyl acrylate and optionally styrene, while the outermost (hard) shell is essentially the same as the matrix polymer, which ensures compatibility and proper bonding with the matrix.

The proportion of polybutyl acrylate in the core or shell of the two- or three-layered core-shell impact modifier is key to the impact modification mechanism and is preferably in the range of 20.0 wt. % to 99.0 wt. %, particularly preferably in the range of 30.0 wt. % up to 98.0 wt. %, even more preferably in the range of 40.0 wt. % to 97.0 wt. %, based on the total weight of the impact modifier.

In addition to particulate impact modifiers that contain butyl acrylate copolymers, it is also possible to use impact modifiers that contain siloxanes. However, the use of such modifiers is less advantageous because their presence in the poly(meth)acrylimide film is generally unfavorable to the print properties of the film.

Methyl methacrylate-butadiene-styrene (MBS) core-shell impact modifiers are also very suitable for use in the film of the present invention due to their excellent compatibility with PMMI. Appropriate impact modifiers are commercially available from several manufacturers such as Arkema France under the brand name Clearstrength® and include products such as Clearstrength® XT100, Clearstrength® 140, Clearstrength® 223, Clearstrength® 303H, Clearstrength® 320, Clearstrength ® 350, Clearstrength® 859. Equally suitable are core-shell MBS impact modifiers available from The Dow Chemical Company under the trademark PARALOID™, such as PARALOID™ EXL-2620, PARALOID™ EXL™ 2650J , PARALOID™ EXL-2690, PARALOID™ EXL-2691, PARALOID™ EXL-2668 and PARALOID™ EXL-3361. The use of these impact modifiers results in PMMI-based films with particularly low haze values and excellent optical clarity.

In some embodiments, the use of a core-shell-shell-shell impact modifier is advantageous in terms of the mechanical properties of the film of the present invention. Suitable impact modifiers are described in detail in patent application WO 2014/035608 A1, the full disclosure of which is incorporated herein by reference.

Thermoplastic impact modifiers have a different mechanism of action than particulate impact modifiers. They are usually mixed with the matrix material. In the event that domains are formed, which is the case, for example, when block copolymers are used, the preferred sizes of such domains, which can be determined, for example, by electron microscopy, correspond to the preferred core-shell particle sizes.

There are various classes of thermoplastic impact modifiers. One of their examples are aliphatic TPUs (thermoplastic polyurethanes), for example, Desmopan® products commercially available from Covestro AG. For example, Desmopan® WDP 85784A, WDP 85092A, WDP 89085A and WDP 89051D TPUs, all of which have refractive indices between 1.490 and 1.500, are particularly suitable as impact modifiers.

An additional class of thermoplastic polymers suitable for use in the thin film of the present invention as impact modifiers are methacrylate and acrylate block copolymers, especially acrylic TPE, which include triblock copolymers of PMMA, poly -n- butyl acrylate and PMMA and which are commercially available under the tradename Kurarity® from Kuraray. Blocks of poly -n- butyl acrylate form nanodomains in the polymer matrix, having a size of 10 nm to 20 nm.

In addition to the thermoplastic impact modifiers described above, it is also possible to use thermoplastic impact modifiers that contain PVDF. However, the use of such modifiers is less advantageous because their presence in a poly(meth)acrylimide film generally tends to degrade the printability of the film.

The film of the present invention typically contains from 2.0 wt. % up to 50.0 wt. %, preferably from 2.5 wt. % up to 40.0 wt. %, more preferably from 4.0 wt. % up to 35.0 wt. %, even more preferably from 6.0 wt. % up to 30.0 wt. % based on the weight of the poly(meth)acrylimide film.

In addition, the total content of poly(meth)acrylimide, polyalkyl(meth)acrylate and impact modifier (hereinafter referred to as " impact poly(meth)acrylimide") in the poly(meth)acrylimide film is usually adjusted to a value of 60 wt. % up to 100 wt. %, more preferably from 65.0 wt. % up to 90.0 wt. %, even more preferably from 70.0 wt. % to 85.0 wt. %, even more preferably from 75.0 wt. % up to 80.0 wt. %, even more preferably from 85.0 wt. % to 100.0 wt. %, even more preferably from 90.0 wt. % to 100.0 wt. %, more preferably from 95.0 wt. % to 100.0 wt. % based on the weight of the poly(meth)acrylimide film.

Inorganic fillers

The presence of inorganic fillers in the poly(meth)acrylimide film of the present invention serves several purposes. The presence of inorganic fillers in these amounts causes the poly(meth)acrylimide film to have a rough surface with a non-glossy appearance and can be easily printed. Printing can be done using essentially any method known in the art, such as laser printing, inkjet printing, flexographic printing, digital printing or screen printing.

In addition, the presence of inorganic fillers makes it possible to give the poly(meth)acrylimide film the desired color and degree of transparency. For example, the presence of titanium dioxide in a poly(meth)acrylimide film will render the film white and essentially opaque.

Finally, as already explained above, the amount of inorganic filler has surprisingly been found to have a strong effect on the properties of the film during handling, in particular on the properties of the residual matrix after the notching step during label manufacture to prevent counterfeiting.

To ensure proper handling of poly(meth)acrylimide film during production and its further use in the manufacture of labels to prevent counterfeiting, it is essential that the content in weight. The % of one or more impact modifiers, n _im , in the poly(meth)acrylimide film obeyed the following relationship:

0.5 × n _f < n _im < 1.8 × n _f ,

wherein n _f is the content in weight. % of one or more inorganic fillers in the poly(meth)acrylimide film.

If the content of one or more impact modifying additives, n _im , in a poly(meth)acrylimide film is lower than 0.5 x n _f , then the film will in principle still be suitable for use in a counterfeit prevention label. However, it will no longer be possible to obtain a plurality of individual anti-counterfeit labels bonded side by side to a backing layer by a method comprising notching the face layer and the PSA layer and then removing the surrounding residual matrix, leaving a plurality of individual labels adhered to the substrate layer (anti-adhesion substrate). Such attempts, most likely, will lead to tearing of the residual matrix.

On the other hand, if the content of one or more impact modifying additives n _im in the poly(meth)acrylimide film is higher than 1.8 * n _f , where n _f is the content of one or more inorganic fillers in the poly( meth)acrylimide film , then the brittleness of the film will be quite low. Therefore, the risk of unauthorized removal of the anti-counterfeiting label from the original substrate will be greatly increased.

In addition, in order to achieve an even better balance between the processability of the poly(meth)acrylimide film and the receptivity of the resulting label to prevent falsification, it is particularly advantageous that the weight content. The % of one or more impact modifiers, n _im , in the poly(meth)acrylimide film obeyed the following relationship:

0.55 × n _f < n _im < 1.6 × n _f ,

wherein n _f is the content in weight. % of one or more inorganic fillers in the poly(meth)acrylimide film.

In addition, in order to achieve an even better balance between the processability of the poly(meth)acrylimide film and the receptivity of the resulting label to prevent falsification, it is particularly advantageous that the weight content. The % of one or more impact modifiers, n _im , in the poly(meth)acrylimide film obeyed the following relationship:

0.6 × n _f < n _im < 1.5 × n _f ,

wherein n _f is the content in weight. % of one or more inorganic fillers in the poly(meth)acrylimide film.

Inorganic fillers for use in the present invention are not particularly limited, and, for example, may be selected from fillers such as titanium dioxide, zinc sulfide, zinc oxide, carbon black, silica, barium sulfate, aluminum trihydroxide, or calcium carbonate, or mixtures thereof.

Theoretically, inorganic fillers are characterized by a residue on a sieve of 45 microns, not more than 0.1 wt. %, i.e., agglomerates with a particle size greater than 45 µm are essentially absent, which is highly advantageous for use in accordance with the present invention. This ensures that the inorganic filler is distributed in the matrix of the poly(meth)acrylate film in a particularly homogeneous manner without the presence of large filler agglomerates, so that the resulting film has a substantially uniform appearance and suitable mechanical properties. In general, the presence of significant amounts of larger filler agglomerates in the film is unfavorable because such agglomerates typically initiate cracks in the film, thereby reducing the random tear strength of the film.

In a preferred embodiment, the inorganic fillers have a weight average particle diameter d50 ranging from 0.05 µm to 10.0 µm, more preferably from 0.1 µm to 5.0 µm, particularly preferably from 0.1 µm to 1, 0 µm, even more preferably 0.1 µm to 0.5 µm. Weighted average particle diameter d_fifty can be determined by a suitable method known to the person skilled in the art, for example, by photon correlation spectroscopy in accordance with DIN ISO 13321 (1996) using a commercially available instrument such as the N5 submicron particle size analyzer from Beckman Coulter Inc or, for particles larger than 1.0 µm, by static light scattering using instrument such as the SZ-10 nanoparticle analyzer from Horiba Scientific Ltd.

In order to ensure particularly uniform dispersibility of the inorganic filler particles in the poly(meth)acrylate-based matrix material, it is further preferred that the oil absorption of the inorganic filler is at least 5 g/100 g of filler, preferably at least 10 g/100 g of filler, and particularly preferably at least 15 g/100 g filler. Even more preferably, the oil absorption of the inorganic filler is at most 100 g/100 g of filler, preferably at most 70 g/100 g of filler, and particularly preferably at most 50 g/100 g of filler. Oil absorption can be determined in accordance with DIN EN ISO 787-5 (1995).

For example, if a white coloration of the film is desired, titanium dioxide may advantageously be used as filler. Generally, rutile or anatase titanium dioxide can be used, where rutile titanium dioxide is particularly preferred due to its low photocatalytic activity. Such materials can be made by the chloride process and are commercially available from various suppliers such as, for example, KRONOS TITAN GmbH (Leverkusen, Germany).

Suitable titanium dioxide fillers may or may not include modifications with water-insoluble oxides of alumina, silicon, zinc, or other means; such reagent materials are specifically added to improve the properties for which the pigment is used. Titanium dioxide based fillers should theoretically be free of diluents such as barium sulfate, clay, magnesium silicate, chalk, etc. Particularly preferred are titanium dioxide based fillers types II, III and IV according to ASTM D476 (2015) classification. .

The film of the present invention typically contains from 0.0 wt. % up to 40.0 wt. %, preferably from 5.0 wt. % up to 40.0 wt. %, more preferably from 8.0 wt. % up to 35.0 wt. %, even more preferably from 10.0 wt.% to 30.0 wt. % of one or more inorganic fillers, based on the weight of the poly(meth)acrylimide film.

UV absorbers and UV stabilizers

UV absorbers and UV stabilizers for use in the film of the present invention are well known and, by way of example, are detailed in Hans Zweifel, Plastics Additives Handbook, Hanser Verlag, 5th Edition, 2001, p. 141ff. UV stabilizers are meant to include UV stabilizers and free radical scavengers.

The UV absorbers may be derived, by way of example, from the group of substituted benzophenones, salicylic acid esters, cinnamic acid esters, oxanilides, benzoxazinones, hydroxyphenylbenzotriazoles, triazines or benzylidenemalonate. The best-known representatives of UV stabilizers/free radical scavengers are represented by a group of hindered amines (hindered amine light stabilizers, HALS).

Advantageously, the combination of UV absorbers and UV stabilizers used in the poly(meth)acrylimide film consists of the following components:

• component A: benzotriazole type UV absorber,

• component B: triazine type UV absorber,

• component C: UV stabilizer (HALS compound).

The individual components can be used in the form of a single substance or in a mixture.

UV absorbers of the benzotriazole type are known in the art and are typically 2-(2'-hydroxyphenyl)benzotriazoles. Suitable compounds include, in particular, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(3',5'-di- tert -butyl-2'-hydroxyphenyl)benzotriazole, 2-(5'- tert -butyl-2'-hydroxyphenyl)benzotriazole, 2-(2'-hydroxy-5'-(1,1,3,3-tetramethylbutyl)phenyl)benzotriazole, 2-(3',5'-di- tert- butyl-2'-hydroxyphenyl)-5-chlorobenzotriazole, 2-(3'- tert -butyl-2'-hydroxy-5'-methylphenyl)-5-chlorobenzotriazole, 2-(3'- sec -butyl-5'- tert -butyl-2'-hydroxyphenyl)benzotriazole, 2-(2'-hydroxy-4'-octyloxyphenyl)benzotriazole, 2-(3',5'-di- tert -amyl-2'-hydroxyphenyl)benzotriazole, 2- (3',5'-bis-(α,α-dimethylbenzyl)-2'-hydroxyphenyl)benzotriazole, 2-(3'- tert -butyl-2'-hydroxy-5'-(2-octyloxycarbonylethyl)phenyl)- 5-chlorobenzotriazole, 2-(3'- tert -butyl-5'-[2-(2-ethylhexyloxy)carbonylethyl]-2'-hydroxyphenyl)-5-chlorobenzotriazole, 2-(3'- tert -butyl-2'-hydroxy-5'-(2-methoxycarbonylethyl)phenyl)-5-chlorobenzotriazole,2-(3'- tert -butyl-2'-hydroxy-5'-(2-meth- H -oxycarbonylethyl)phenyl)benzotriazole, 2 -(3'- tert -butyl-2'-hydroxy -5'-(2-octyloxycarbonylethyl)phenyl)benzotriazole, 2-(3'- tert -butyl-5'-[2-(2-ethylhexyloxy)carbonylethyl]-2'-hydroxyphenyl)benzotriazole, 2-(3'- dodecyl-2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(3'- tert -butyl-2'-hydroxy-5'-(2-isooctyloxycarbonylethyl)phenylbenzotriazole, 2,2'-methylene-bis[4- (1,1,3,3-tetramethylbutyl)-6-benzotriazol-2-ylphenol]; transesterification product of 2-[3'- tert -butyl-5'-(2-methoxycarbonylethyl)-2'-hydroxyphenyl]-2 H -benzotriazole with polyethylene glycol 300; [R-CH2CH2-COO-CH2CH2-, where R = 3'- tert -butyl-4'-hydroxy-5'-2 H- benzotriazol-2-ylphenyl, 2-[2'-hydroxy-3'-(α ,α-dimethylbenzyl)-5'-(1,1,3,3-tetramethylbutyl)phenyl]benzotriazole;2-[2'-hydroxy-3'-(1,1,3,3-tetramethylbutyl)-5'-(α,α-dimethylbenzyl)phenyl]benzotriazole. Additional examples of benzotriazole type UV absorbers that can be used are 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-[2-hydroxy-3,5-di(α,α-dimethylbenzyl)phenyl]benzotriazole, 2 -(2-hydroxy-3,5-di- tert -butylphenyl)benzotriazole, 2-(2-hydroxy-3,5-butyl-5-methylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3.5 -di- tert -butylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3,5-di- tert -amylphenyl)benzotriazole, 2-(2-hydroxy-5- tert -butylphenyl)benzotriazole, 2-(2 -hydroxy-3- sec -butyl-5- tert -butylphenyl)benzotriazole and 2-(2-hydroxy-5- tert -octylphenyl)benzotriazole, phenol, 2,2'-methylenebis[6-(2H- benzotriazole -2 -yl)-4-(1,1,3,3-tetramethylbutyl)].

These compounds are commercially available from BASF SE (Ludwigshafen, Germany), for example, in the form of Tinuvin® 360 and Tinuvin® 234 products.

Useful amounts of UV absorbers of the benzotriazole type range from 0.1 wt. % up to 5.0 wt. %, preferably from 0.2 wt. % up to 3.0 wt. % and particularly preferably from 0.5 wt. % to 2.0 wt. % based on the weight of the poly(meth)acrylimide film. Mixtures of different UV absorbers of the benzotriazole type can also be used.

Triazine type UV absorbers are typically 2-(2-hydroxyphenyl)-1,3,5-triazines. Preferably used 2-(2-hydroxyphenyl)-1,3,5-triazines include among other 2,4,6-tris(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-octyloxyphenyl)-4,6-bis(2,4-dimethylphenyl) -1,3,5-triazine, 2-(2,4-dihydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2,4-bis(2-hydroxy- 4-propyloxyphenyl)-6-(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-octyloxyphenyl)-4,6-bis(4-methylphenyl)-1,3, 5-triazine, 2-(2-hydroxy-4-dodecyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-tridecyloxyphenyl)-4 ,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[2-hydroxy-4-(2-hydroxy-3-butyloxypropoxy)phenyl]-4,6-bis(2,4 -dimethyl)-1,3,5-triazine, 2-[2-hydroxy-4-(2-hydroxy-3-octyloxypropyloxy)phenyl]-4,6-bis(2,4-dimethyl)-1,3, 5-triazine, 2-[4-(dodecyloxy/tridecyloxy-2-hydroxypropoxy)-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[2- hydroxy-4-(2-hydroxy-3-dodecyloxypropoxy)phenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-hexyloxy)phenyl- 4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-methoxyphenyl)-4,6-diphenyl-1,3,5-triazine n, 2,4,6-tris[2-hydroxy-4-(3-butoxy-2-hydroxypropoxy)phenyl]-1,3,5-triazine, 2-(2-hydroxyphenyl)-4-(4-methoxyphenyl) )-6-phenyl-1,3,5-triazine, 2-{2-hydroxy-4-[3-(2-ethylhexyl-1-oxy)-2-hydroxypropyloxy]phenyl}-4,6-bis(2 ,4-di-methylphenyl)-1,3,5-triazine, 2,4-bis(4-[2-ethylhexyloxy]-2-hydroxyphenyl)-6-(4-methoxyphenyl)-1,3,5-triazine . Triazine type UV absorbers such as 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-hexyloxyphenol can also be used.

These compounds are commercially available, for example from BASF SE (Ludwigshafen, Germany) under the trademarks Tinuvin® 1600, Tinuvin® 1577 or Tinuvin® 1545.

The amounts of triazine type UV absorber are from 0.1 to 5.0 wt. %, preferably from 0.2 to 3.0 wt. % and most preferably from 0.5 to 2.0 wt. % based on the weight of the film. It is also possible to use mixtures of different triazine type UV absorbers.

The film of the present invention may further contain one or more UV stabilizers, which typically act as antioxidants, radical scavengers, etc. Particularly preferred UV stabilizers are hindered phenols and additives such as HALS.

Hindered amines, HALS UV stabilizers ( Hindered A mine L ight Stabilizer), are known per se. They can be used to slow down the aging phenomenon in paints and plastics, especially polyolefin-based plastics (Kunststoffe, 74 (1984) 10, pp. 620-623; Farbe + Lack, vol. 96, 9/1990, pp. 689-693 ). The tetramethylpiperidine group present in the HALS compounds is responsible for the stabilizing effect. This class of compounds may have no substitution on the nitrogen atom of piperidine, or substitution with alkyl or acyl groups on the nitrogen atom of piperidine. Hindered amines do not absorb radiation in the UV region. They trap free radicals that are formed, whereas UV absorbers are unable to do so. Examples of HALS compounds which have a stabilizing effect and which can also be used as mixtures are bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, 8-acetyl-3-dodecyl-7,7,9, 9-tetramethyl-1,3,8-triazaspiro(4,5)-decane-2,5-dione, bis(2,2,6,6-tetramethyl-4-piperidyl)succinate, poly( N -β-hydroxyethyl -2,2,6,6-tetramethyl-4-hydroxypiperidine succinate) or bis( N -methyl-2,2,6,6-tetramethyl-4-piperidyl)sebacate.

These compounds are commercially available, for example from BASF SE (Ludwigshafen, Germany) under the trademarks Tinuvin® 123, Tinuvin® 144 or Tinuvin® 292.

Applied amounts of HALS compounds in the film are usually from 0.0 to 5.0 wt. %, preferably from 0.1 to 3.0 wt. % and particularly preferably from 0.2 to 2.0 wt. % based on the weight of the film. It is also possible to use mixtures of different HALS compounds.

In general, the film of the present invention typically contains from 0.0 wt. % up to 5.0 wt. % of one or more UV absorbers and from 0.0 wt. % up to 5.0 wt. % of one or more UV stabilizers, based on the weight of the poly(meth)acrylimide film.

Detailed configuration of a line preferably used to produce films according to the present invention

The poly(meth)acrylimide film used in accordance with the present invention is preferably produced by an extrusion process. Unlike the film produced by the solution coating process, the extruded poly(meth)acrylimide film is substantially free of volatile organic compounds such as solvents, which is highly advantageous for toxicity and environmental reasons.

The above-described components of the poly(meth)acrylimide film can be mixed before or even during the extrusion step.

For the extrusion of poly(meth)acrylimide film, a line containing at least the following components can be used:

extruder,

melt pump,

optional installation for melt filtration,

optional static mixing element,

flat die for film production,

machine calender or chill roll and

winding device.

The extrusion of polymers into films is well known and is described, for example, in Kunststoffextrusionstechnik II, Hanser Verlag, 1986, pp. 125ff.

In the process of the present invention, the hot melt is extruded from the extruder die onto a nip between two polishing rolls or onto a chill roll. The optimum melt temperature depends, for example, on the composition of the mixture and can therefore vary within wide limits. Preferred sand temperatures up to the die entry point are in the range of 170 to 320°C, more preferably in the range of 200 to 290°C, and particularly preferably in the range of 220 to 280°C. The temperature of the polishing rolls is preferably less than or equal to 150°C, more preferably 60°C to 140°C.

In one embodiment, the temperature of the head is higher than the temperature of the mixture before entering the head. The head temperature is preferably set to 10°C, more preferably 20°C and most preferably 30°C higher than the temperature of the mixture before entering the head. Therefore, preferred head temperatures are in the range of 160°C to 330°C, more preferably 190°C to 300°C.

The machine calender can consist of two or three polishing rolls. Polishing rolls are well known in the art and are used to achieve greater gloss. However, rolls other than polishing rolls for example, matting rolls can also be used in the method of the present invention. The gap between the first two polishing rolls forms a sheet, which becomes a film through simultaneous cooling.

Alternative chill rolls are also known to those skilled in the art. In this case, the sheet of melt can be deposited on one chill roller which moves it further. The chill rolls are preferably located above the machine calenders.

Alternatively, extrusion can be carried out by a particularly advantageous method using the equipment described in patent applications US 2016/0159995 A1 and US 2017/0306188 A1, the full disclosure of which is incorporated herein by reference.

Particularly good surface quality of the film can be achieved with a die and roller with chromium-plated surfaces, and especially with these chromium-plated surfaces with a roughness Ra (according to DIN 4768 (1990)) of less than 0.10 µm, preferably less than 0.08 µm.

To ensure that the poly(meth)acrylimide film is substantially free of impurities, a filter may optionally be placed prior to entering the melt die. The mesh size of the filter sieve is generally influenced by the raw materials used and can thus vary widely. Sieve mesh sizes are typically in the range of 300 µm to 20 µm. Filters with two or more screens with different mesh sizes can also be placed in front of the head entry point. These filters are commercially available. In order to obtain films of high quality, it is preferable, moreover, to use particularly pure raw materials.

Optionally, the static mixing element can also be installed upstream of the film flat die. This mixing element can be used to mix components such as pigments, stabilizers or additives into a polymer melt, or up to 5 wt. % of the second polymer, for example in the form of a melt, can be mixed from the second extruder into the material.

The pressure with which the molten mixture is forced into the die can be controlled, for example, by the speed of the screw. The pressure is usually in the range of 40 bar to 300 bar, and this does not limit the method of the present invention. Therefore, the speed at which films can be produced in accordance with the present invention is generally greater than 5 m/min, more preferably greater than 10 m/min.

In order to ensure a particularly uniform movement of the melt upstream of the film die, a melt pump can be additionally provided.

In order to further improve the handling of the extruded poly(meth)acrylimide film of the present invention, advantageously if the backing layer 5 is bonded to the poly(meth)acrylimide film 6 from step i) downstream of the extruder at a temperature lower than the glass transition temperature of the poly( meth)acrylimide, whereby a layered material 4 is obtained.

The resulting laminate 4 will typically consist of the following two layers ( see Fig. 2):

• layer formed by poly(meth)acrylimide film 6 ; and

• lining layer 5 .

In one embodiment, the backing layer is self-adhesive. Such a self-adhesive liner typically contains an adhesive layer which can advantageously be used to bond the liner to poly(meth)acrylimide films 6 having a matte surface.

In a further embodiment, the backing layer comprises a polyethylene-based copolymer layer instead of an adhesive layer. Such linings are predominantly used for poly(meth)acrylimide films 6 having a glossy surface.

In order to ensure proper mechanical stability and in particular high tear strength of the laminate 4 , it is advantageous if the backing layer preferably has a tear resistance measured in accordance with ASTM D1004 (2013) of 50 N to 500 N. Backing layer material is not particularly limited provided that the backing layer has sufficient tear resistance, and may be selected from one of the following: polyethylene, polypropylene, polyethylene terephthalate, or mixtures thereof, where biaxially oriented polypropylene or biaxially oriented polyethylene terephthalate are particularly preferred.

In subsequent process steps, the laminate will undergo the step of bonding an adhesive layer, optionally a release layer, and a backing layer to form a label blank. Such method steps are well known to the person skilled in the art and are explained in detail, for example, in patent applications US 2004/0091657 A1 and US 2011/0132522 A1.

Typically, the adhesive layer essentially consists of a pressure-sensitive adhesive (PSA). The backing layer usually contains a paper or plastic film material and may be coated with a separating layer. Various release coating compositions are known, such as those described in US 6406787. Compositions based on adhesives other than PSA can also be used, in particular for embodiments where the shape of the substrate layer is porous (e.g. paper), while the shape of the substrate is located on the invisible surface of the label.

The PSAs suitable for the present invention are preferably selected from the group consisting of polymers and copolymers based on alkyl acrylates; copolymers of alkyl acrylates with acrylic acid; terpolymers based on alkyl acrylates, acrylic acid and vinyl lactates; polymers and copolymers based on alkyl vinyl ethers; polyisoalkylenes; polyalkyl dienes; copolymers of alkyldiene and styrene; block copolymers of styrene, isoprene and styrene; polydialkylsiloxanes; polyalkylphenylsiloxanes; natural rubbers; synthetic rubbers; chlorinated rubbers; crepe latex; rosin; coumarone resins; alkyd polymers and polyacrylate esters and mixtures thereof. Examples include polyisobutylenes, polybutadienes or copolymers of butadiene and styrene and mixtures thereof (such polymers and copolymers preferably do not contain reactive moieties, i.e. they do not oxidize in the presence of air); silicone-based compounds such as polydimethylsiloxane and polymethylphenylsiloxane combined with other resins and/or oils.

Other suitable PSAs also include tackified thermoplastic resins and tackified thermoplastic elastomers wherein the tackifier provides one or more compounds that increase the tackiness of the composition. An example of a high tack thermoplastic resin useful as a high strength PSA is a combination of a vinyl acetate-ethylene copolymer known under the trade name VYNATHENE EY 902-30 (available from Quantum Chemicals, Cincinnati, Ohio) with substantially equal parts of tackifiers, known by the trade names PICCOTEX LC (water colorless thermoplastic resin obtained by copolymerization of vinyltoluene and alpha-methylstyrene monomers, characterized by a ring and ball softening point of approximately 87°C to 95°C, available from Hercules Incorporated, Wilmington, Delaware) and WINGTACK 10 (liquid aliphatic C-5 hydrocarbon petroleum resin available from Goodyear Chemical) and an organic solvent such as toluene. An example of a high tack thermoplastic elastomer useful as a high strength PSA is the combination of a block copolymer of styrene, poly(ethylenebutylene) and styrene known under the tradename KRATON G1657 (available from Shell Chemicals) with one or more low molecular weight hydrocarbon resins known as the trade name REGALREZ (from Hercules), and an organic solvent such as toluene. Both of these formulations can be applied as a coating using a knife coater and either air dried or air dried followed by oven drying. Obviously, the present invention is not limited to the use of such specific combinations of thermoplastic resins, thermoplastic elastomers and tackifiers.

Some preferred PSAs in the present invention are characterized by long shelf life and resistance to atmospheric tack loss, and include the acrylic copolymer adhesives disclosed in U.S. Patent No. Re24906. 5:4.5 (measured for each in parts by weight). Another preferred adhesive is a 90:10 weight ratio copolymer of these two monomers. Still other preferred adhesives are ethyl acrylate, butyl acrylate and acrylic acid terpolymers; copolymers of isooctyl acrylate and acrylamide; and terpolymers of isooctyl acrylate, vinyl acetate and acrylic acid.

Acrylic PSAs can be applied as a coating in a coating composition containing an organic solvent, such as a heptane:isopropanol solvent mixture, and then the solvent is evaporated, leaving a coating of pressure-sensitive adhesive. The thickness of this layer is preferably from about 0.038 centimeters (cm) to about 0.11 centimeters (5-15 mils) if the substrate is a reflective material.

PSAs useful in the present invention can also be described as having a 180° peel strength ranging from about 10 to about 1000 g/cm, more preferably at least about 50 g/cm. For strong PSAs, the 180° peel strength typically ranges from about 200 gsm to about 600 gsm as measured using a standard testing procedure. In this procedure, the force required to remove (ie, peel) the PSA-coated substrate from the test substrate, if the PSA-coated substrate is peeled off from the test substrate, is defined as the " peel strength " value. A standard glass plate is cleaned using a solvent (such as one wash with diacetone alcohol followed by three washes with n-heptane). The PSA backed sample is then applied with slight force along the center of a standard glass plate, PSA side down. The sample is then rolled once with a 2.04 kg hand roller. The standard glass plate is then attached to the horizontal plate in a standard peel strength tester such as known under the trade name "IMASS". Then one end of the specimen is attached to the hook which is part of the peel strength tester. The sample is peeled off the standard glass plate at an angle of 180° (i.e. (e. one end of the specimen is pulled towards the other corner) by moving the plate horizontally at a speed of 228.6 cm/min and recording the required force in g/cm of the specimen width, for various holding times.

The separating layer 8 , which is usually a siloxane coating, has the function of reducing the adhesion between the adhesive layer 7 and the substrate layer 9 . Typically, the separating layer 8 achieves a kinetic friction coefficient of less than 0.35, preferably less than 0.25, as determined in accordance with ASTM D1894 (2014).

Finally, the label blank will be scored to form a plurality of individual anti-counterfeiting self-adhesive labels associated with the backing layer 9 . The notching can be performed by mechanical cutting with a punch, as described in US 2011/0132522 A1, or using a laser. In a subsequent step, the residual matrix surrounding the individual self-adhesive labels to prevent counterfeiting will be peeled off from the backing layer without any risk of tearing.

To minimize waste generation, the distance between individual labels (i.e. residual matrix band width) is kept in the range of 1.0 mm to 10.0 mm, more preferably 2.0 mm to 8.0 mm, even more preferably 3.0 mm to 5.0 mm. As explained above, undesirable tearing of the residual matrix does not occur. Typically, the separation force during this operation is less than 30 g/in, preferably less than 20 g/in, even more preferably 1 g/in to 10 g/in, as measured using a T-peel test with tape. 7475 tesaband® from tesa SE (Norderstedt, Germany).

Anti-Falsification Labels

The anti-counterfeiting label 2 of the present invention contains at least the following layers in this order ( see FIG. 3):

a) layer 6 consisting of the extruded poly(meth)acrylimide film described above;

b) adhesive layer 7 ;

c) separating layer 8 and

d) backing layer 9 .

Generally, the counterfeit prevention label of the present invention has a thickness of 50.0 µm to 300.0 µm, more preferably 100.0 µm to 200.0 µm.

In the usual embodiment

• the PMMI layer 6 may have a thickness of 20 µm to 100 µm, more preferably 30 µm to 75 µm, even more preferably 40 µm to 60 µm;

• the adhesive layer 7 may have a thickness of 10 µm to 40 µm, more preferably 20 µm to 30 µm;

• the separating layer 8 may have a thickness of 0.01 µm to 1.5 µm, preferably 0.5 µm to 1.2 µm, more preferably 0.6 µm to 0.8 µm; and

• the substrate layer 9 may have a thickness of 20 µm to 70 µm, preferably 30 µm to 50 µm.

In principle, the size of the anti-counterfeiting labels can be freely chosen and is limited only by the dimensions of the extrusion head and/or machine calender used to produce them. This means that the formats can be chosen essentially freely.

The cutting and notching of the poly(meth)acrylimide film is preferably performed by punch cutting, cutting, laser cutting or laser cutting. Particular preference is given to laser cutting or cutting by laser punching.

Optionally, but not necessarily, poly(meth)acrylimide films made in accordance with the present invention may additionally be provided with edges, cuts, slits, or perforations or serifs to further assist in the destruction of labels when they are attempted to be tampered with. However, such additional measures are not mandatory.

Anti-tampering labels are great for making electronic product identification labels, hidden car labels, chip cards, heat-resistant documents and seals. One illustrative application is, for example, barcode labels on various parts of an automobile engine. The labels can withstand engine operating temperatures without any noticeable shrinkage, and are also chemically resistant to fluids such as brake fluid, hydraulic fluid, engine oil, etc. The label will be destroyed if an unauthorized attempt is made to separate it from the engine part in order to transfer it to a non-genuine engine replacement part.

As a further example, the labels of the present invention may contain a vehicle identification number and may advantageously be applied under the hood of a vehicle. Unauthorized attempt to remove the label from a vehicle in order to attach it to another vehicle will destroy the label.

In conclusion, the following aspects and embodiments {1} - {15} of the present invention have proven to be particularly advantageous.

{1} A poly(meth)acrylimide film for use in a counterfeit prevention label, where the poly(meth)acrylimide film contains

from 30.0 wt. % up to 98.0 wt. % poly(meth)acrylimide;

from 2.0 wt. % up to 50.0 wt. % of one or more impact modifiers;

from 0.0 wt. % up to 30.0 wt. % polyalkyl(meth)acrylate;

from 0.0 wt. % up to 40.0 wt. % of one or more inorganic fillers;

from 0.0 wt. % up to 5.0 wt. % of one or more UV absorbers and

from 0.0 wt. % up to 5.0 wt. % of one or more UV stabilizers, based on the weight of the poly(meth)acrylimide film;

where poly(meth)acrylimide contains at least 50 wt. %, preferably at least 60 wt. %, most preferably at least 70 wt. % based on the weight of poly(meth)acrylimide repeating units of formula (I),

wherein R ¹ and R ² are independently selected from hydrogen and a methyl group, preferably R ¹ and R ² are a methyl group, and

R ³ is hydrogen or a C ₁ -C ₄ alkyl group, preferably a methyl group; and

while the total content of poly(meth)acrylimide, polyalkyl(meth)acrylate and an additive that modifies impact strength is from 60.0 wt. % to 100.0 wt. % based on the weight of the poly(meth)acrylimide film.

{2} The poly(meth)acrylimide film according to {1}, wherein the poly(meth)acrylimide film contains

from 30.0 wt. % to 92.5 wt. % poly(meth)acrylimide;

from 2.5 wt. % up to 40.0 wt. % of one or more impact modifiers;

from 0.0 wt. % up to 30.0 wt. % polyalkyl(meth)acrylate;

from 5.0 wt. % up to 40.0 wt. % of one or more inorganic fillers;

from 0.0 wt. % up to 5.0 wt. % of one or more UV absorbers and

from 0.0 wt. % up to 5.0 wt. % of one or more UV stabilizers, based on the weight of the poly(meth)acrylimide film;

while the total content of poly(meth)acrylimide, polyalkyl(meth)acrylate and an additive that modifies impact strength is from 60.0 wt. % up to 95.0 wt. % based on the weight of the poly(meth)acrylimide film; and wherein

content in weight. The % of one or more impact modifiers, n _im , in a poly(meth)acrylimide film is described by the following relationship:

0.5 × n _f < n _im < 1.8 × n _f ,

wherein n _f is the content in weight. % of one or more inorganic fillers in the poly(meth)acrylimide film.

{3} The poly(meth)acrylimide film according to {1} or {2}, wherein the poly(meth)acrylimide film has a thickness of 15.0 µm to 120.0 µm, and

a nominal elongation at break between 3.0% and 30%, measured according to DIN EN ISO 527-3/2/100 (2003) using a thin film of 50.0 µm, and

tensile stress from 20.0 MPa to 70.0 MPa, measured in accordance with DIN EN ISO 527-3/2/100 (2003) using a 50.0 µm thin film.

{4} A poly(meth)acrylimide film according to any one of paragraphs. {1}-{3}, wherein the poly(meth)acrylimide film has a tear propagation resistance measured in accordance with ASTM D1938 (2014) using a 50.0 µm thin film of 0.01 N/mm to 1, 50 N/mm.

{5} Poly(meth)acrylimide film according to any one of paragraphs. {1}-{4}, where content is in weight. The % of one or more impact modifiers, n _im , in a poly(meth)acrylimide film is described by the following relationship:

0.6 × n _f < n _im < 1.5 × n _f ,

wherein n _f is the content in weight. % of one or more inorganic fillers in the poly(meth)acrylimide film.

{6} A poly(meth)acrylimide film according to any one of paragraphs. {1}-{5}, characterized in that one or more inorganic fillers are selected from titanium dioxide, silicon dioxide, zinc oxide, zinc sulfide, barium sulfate, carbon black, aluminum trihydroxide or calcium carbonate.

{7} A poly(meth)acrylimide film according to any one of paragraphs. {1}-{6}, characterized in that the poly(meth)acrylimide has an average molar mass Mw of 80,000 g/mol to 200,000 g/mol, preferably 90,000 g/mol to 150,000 g/mol.

{8} A counterfeit prevention label comprising a poly(meth)acrylimide film according to any one of paragraphs. {1}-{7}.

{9} Anti-counterfeiting label according to {8}, characterized in that the anti-counterfeiting label comprises at least the following layers in this order:

a) a layer consisting of a poly(meth)acrylimide film according to any one of paragraphs. {1}-{7}, preferably having a thickness of 40.0 µm to 60.0 µm;

b) an adhesive layer, preferably having a thickness of 20.0 µm to 30.0 µm;

c) a separating layer, preferably having a thickness of 0.6 µm to 0.8 µm; and

d) a support layer, preferably having a thickness of 30.0 µm to 50.0 µm;

and/or the counterfeit prevention label is characterized by a thickness of 50.0 µm to 300.0 µm.

{10} A laminate for manufacturing a counterfeit prevention label according to {8} or {9}, wherein the laminate comprises at least the following layers:

a) a backing layer, preferably having a tear resistance of 50 N to 500 N, measured in accordance with ASTM D1004 (2013) using a 50.0 µm thin film; and

b) a layer consisting of a poly(meth)acrylimide film according to any one of paragraphs. {1}-{7}.

{11} Laminated material according to {10}, wherein the backing layer essentially consists of a polymeric material selected from the group consisting of polyethylene, polypropylene and polyethylene terephthalate, preferably biaxially oriented polypropylene or biaxially oriented polyethylene terephthalate.

{12} A method for manufacturing a laminate according to {10} or {11}, wherein the method includes at least the following steps:

i) obtaining a poly(meth)acrylimide film according to any one of paragraphs. {1}-{7} using an extruder to obtain a poly(meth)acrylimide film; and

ii) bonding the backing layer to the poly(meth)acrylimide film from step i) downstream of the extruder.

{13} The method according to {12}, wherein the laminate obtained in step ii) is passed between a plurality of rolls, wherein at least one roll facing the poly(meth)acrylimide film is a chill roll.

{14} A method for manufacturing a counterfeit prevention label according to {8} or {9}, wherein the method includes at least the following steps:

i) obtaining a poly(meth)acrylimide film according to any one of paragraphs. {1}-{7} using an extruder;

ii) bonding the backing layer to the poly(meth)acrylimide film from step i) downstream of the extruder to form a laminate;

iii) bonding an adhesive layer, optionally a release layer and a backing layer to the laminate from step ii), whereby a label blank is obtained; and

iv) notching the label blank obtained in step iii) and removing the resulting residual matrix, thereby obtaining a plurality of individual self-adhesive labels on the backing layer to prevent counterfeiting.

{15} Application of a label to prevent falsification in accordance with paragraphs. {8}-{9} for chip cards, documents, anti-counterfeiting labels, electronic product identification labels, hidden car labels, document seals or price tags.

Examples

Example 1 (comparative)

A PMMA-based film having a total thickness of 50 μm was obtained using a formulated blend with the following composition:

a) 30.0 wt. % material containing 47.0 wt. % acrylic impact modifier, core-sheath-sheath type, based on butyl acrylate,

b) 48.67 wt. % PLEXIGLAS® 7N available from Evonik Performance Materials GmbH and

c) 21.33 wt. % titanium dioxide available from KRONOS TITAN GmbH.

The extrusion was carried out at an extrusion speed of 7.3 m/min using a single screw extruder with a screw diameter of 35 mm from Dr. Collin GmbH (Ebersberg, Germany) under the following conditions.

Screw temperature in extruder: 240°C to 270°C

Head temperature: 240°C to 260°C

Melt temperature in the head: 240 C to 260 C

Roll temperature: 50°C to 120 C

The extruded film exhibited an elongation at break of 4 to 6% in the direction of extrusion.

The extruded film was then used to produce self-adhesive anti-counterfeit labels using an MPS EF Flexo label machine from MPS Systems B.V. (Arnhem, the Netherlands).

The film can be successfully used for the manufacture of self-adhesive labels to prevent counterfeiting. Undesired tearing of the residual matrix did not occur.

Tear resistance tests were performed using a Zwick Roell Z005 test system available from Zwick GmbH & Co. KG (Ulm, Germany) with 4 identical samples, with 5 tests performed for each sample.

The tear resistance, measured using specimens having a width of 10 mm to 20 mm, in accordance with ASTM D1004 (2013) in the direction of film extrusion, ranged from 5.8 N to 7.0 N.

Sample shrinkage measured at 120° C. (30 minutes) according to EN ISO 11501 (2004) was 6.6% in the extrusion direction and 1.1% in the transverse direction. Materials having such high shrinkage at elevated temperatures are generally not suitable for marking vehicle parts that can reach such temperatures.

Example 2 (in accordance with the present invention)

A film having a total thickness of 50 µm was obtained using a formulated mixture with the following composition:

a) 30.0 wt. % material containing 47 wt. % acrylic impact modifier, core-sheath-sheath type, based on butyl acrylate,

b) 55.0 wt. % material containing

40 wt. % titanium dioxide available from KRONOS TITAN GmbH and

60 wt% PLEXIMID® TT50 available from Evonik Performance Materials GmbH,

c) 15.0 wt% PLEXIMID® TT50 available from Evonik Performance Materials GmbH.

The extrusion was carried out at an extrusion speed of 7.3 m/min using a single screw extruder with a screw diameter of 35 mm from Dr. Collin GmbH (Ebersberg, Germany) under the following conditions.

Screw temperature in extruder: 270 C to 285°C

Head temperature: 270 C to 275 C

Melt head temperature: 270 C to 275 C

Roll temperature: 50 C to 120 C

The extruded film had a nominal elongation at break of 7.4% and a tensile strength of 59.1 MPa in the direction of extrusion.

The extruded film was then used to produce self-adhesive anti-counterfeit labels using an MPS EF Flexo label machine from MPS Systems B.V. (Arnhem, the Netherlands).

The film can be successfully used for the manufacture of self-adhesive labels to prevent counterfeiting. Undesired tearing of the residual matrix did not occur.

Sample shrinkage measured at 120° C. (30 minutes) according to EN ISO 11501 (2004) was 0.3% in the extrusion direction and 0.2% in the transverse direction. The label can advantageously be used for marking parts of vehicles that are operated at such temperatures.

Example 3 (in accordance with the present invention)

A film having a total thickness of 50 µm was obtained using a formulated mixture with the following composition:

a) 15.0 wt. % acrylic impact modifier, core-sheath-sheath type, based on butyl acrylate,

b) 55.0 wt. % material containing

40 wt. % titanium dioxide available from KRONOS TITAN GmbH and

60 wt% PLEXIMID® TT50 available from Evonik Performance Materials GmbH,

c) 30.0 wt% PLEXIMID® TT50 available from Evonik Performance Materials GmbH.

The extrusion was carried out at an extrusion speed of 7.3 m/min using a single screw extruder with a screw diameter of 35 mm from Dr. Collin GmbH (Ebersberg, Germany) under the following conditions.

Extruder screw temperature: 270 C to 285 C

Head temperature: 270°C to 275°C

Melt head temperature: 270 C to 275 C

Roll temperature: 50 C to 120 C

The extruded film had a nominal elongation at break of 11.1% and a tensile strength of 54.5 MPa in the direction of extrusion.

The extruded film was then used to produce self-adhesive anti-counterfeit labels using an MPS EF Flexo label machine from MPS Systems B.V. (Arnhem, the Netherlands).

The film can be successfully used for the manufacture of self-adhesive labels to prevent counterfeiting. Undesired tearing of the residual matrix did not occur.

Sample shrinkage measured at 120° C. (30 minutes) according to EN ISO 11501 (2004) was 0.1% in the extrusion direction and 0.1% in the transverse direction. The label can advantageously be used to mark various parts of vehicles that operate at these temperatures.

Example 4 (in accordance with the present invention)

A film having a total thickness of 50 µm was obtained using a formulated mixture with the following composition:

a) 20.0 wt. % acrylic impact modifier, core-sheath-sheath type, based on butyl acrylate,

b) 55.0 wt. % material containing

40 wt. % titanium dioxide available from KRONOS TITAN GmbH and

60 wt% PLEXIMID® TT50 available from Evonik Performance Materials GmbH,

c) 25.0 wt% PLEXIMID® TT50 available from Evonik Performance Materials GmbH.

The extrusion was carried out at an extrusion speed of 7.3 m/min using a single screw extruder with a screw diameter of 35 mm from Dr. Collin GmbH (Ebersberg, Germany) under the following conditions.

Screw temperature in extruder: 270 C to 285°C

Head temperature: 270 C to 275 C

Melt head temperature: 270 C to 275 C

Roll temperature: 50°C to 120 C

The extruded film had a nominal elongation at break of 12.8% and a tensile strength of 50.3 MPa in the direction of extrusion.

The extruded film was then used to produce self-adhesive anti-counterfeit labels using an MPS EF Flexo label machine from MPS Systems B.V. (Arnhem, the Netherlands).

The film can be successfully used for the manufacture of self-adhesive labels to prevent counterfeiting. Undesired tearing of the residual matrix did not occur.

Sample shrinkage measured at 120° C. (30 minutes) according to EN ISO 11501 (2004) was 0.2% in the extrusion direction and 0.1% in the transverse direction. The label can advantageously be used to mark various parts of vehicles that operate at these temperatures.

Example 5 (in accordance with the present invention)

A film having a total thickness of 50 µm was obtained using a formulated mixture with the following composition:

a) 25.0 wt. % acrylic impact modifier, core-sheath-sheath type, based on butyl acrylate,

b) 55.0 wt. % material containing

40 wt. % titanium dioxide available from KRONOS TITAN GmbH and

60 wt% PLEXIMID® TT50 available from Evonik Performance Materials GmbH,

c) 20.0 wt% PLEXIMID® TT50 available from Evonik Performance Materials GmbH.

The extrusion was carried out at an extrusion speed of 7.3 m/min using a single screw extruder with a screw diameter of 35 mm from Dr. Collin GmbH (Ebersberg, Germany) under the following conditions.

Extruder screw temperature: 270 C to 285 C

Head temperature: 270 C to 275 C

Melt head temperature: 270 C to 275 C

Roll temperature: 50 C to 120 C

The extruded film had a nominal elongation at break of 18.2% and a tensile strength of 45.2 MPa in the direction of extrusion.

The extruded film was then used to produce self-adhesive anti-counterfeit labels using an MPS EF Flexo label machine from MPS Systems B.V. (Arnhem, the Netherlands).

The film can be successfully used for the manufacture of self-adhesive labels to prevent counterfeiting. Undesired tearing of the residual matrix did not occur.

Sample shrinkage measured at 120° C. (30 minutes) according to EN ISO 11501 (2004) was 0.4% in the extrusion direction and 0.1% in the transverse direction. The label can advantageously be used to mark various parts of vehicles that operate at these temperatures.

Example 6 (in accordance with the present invention)

A film having a total thickness of 50 µm was obtained using a formulated mixture with the following composition:

a) 10.0 wt. % acrylic impact modifier, core-sheath-sheath type, based on butyl acrylate,

b) 90.0 wt% PLEXIMID® TT50 available from Evonik Performance Materials GmbH.

The extrusion was carried out at an extrusion speed of 7.3 m/min using a single screw extruder with a screw diameter of 35 mm from Dr. Collin GmbH (Ebersberg, Germany) under the following conditions.

Extruder screw temperature: 270 C to 285 C

Head temperature: 270°C to 275°C

Melt head temperature: 270°C to 275°C

Roll temperature: 50 C to 120 C

The extruded film had a nominal elongation at break of 5.6%, a tensile strength of 85.1 MPa in the extrusion direction, and a nominal elongation at break of 4.5% and a tensile strength of 54.8 MPa in the transverse direction.

The haze of the film was 12.60%.

Example 7 (in accordance with the present invention)

A film having a total thickness of 50 µm was obtained using a formulated mixture with the following composition:

a) 10.0 wt. % butyl acrylate-based impact modifier, core-shell type,

b) 90.0 wt% PLEXIMID® TT50 available from Evonik Performance Materials GmbH.

The extrusion was carried out at an extrusion speed of 7.3 m/min using a single screw extruder with a screw diameter of 35 mm from Dr. Collin GmbH (Ebersberg, Germany) under the following conditions.

Extruder screw temperature: 270 C to 285 C

Head temperature: 270 C to 275 C

Melt head temperature: 270 C to 275 C

Roll temperature: 50 C to 120 C

The extruded film had a nominal elongation at break of 5.4%, a tensile strength of 48.7 MPa in the extrusion direction, and a nominal elongation at break of 4.0% and a tensile strength of 11.0 MPa in the transverse direction.

The haze of the film was 7.22%.

Example 8 (in accordance with the present invention)

A film having a total thickness of 50 µm was obtained using a formulated mixture with the following composition:

a) 10.0 wt. % impact modifier, core-shell type based on MBS,

b) 90.0 wt% PLEXIMID® TT50 available from Evonik Performance Materials GmbH.

The extrusion was carried out at an extrusion speed of 7.3 m/min using a single screw extruder with a screw diameter of 35 mm from Dr. Collin GmbH (Ebersberg, Germany) under the following conditions.

Screw temperature in extruder: 270°C to 285°C

Head temperature: 270 C to 275 C

Melt head temperature: 270 C to 275 C

Roll temperature: 50°C to 120°C

The extruded film had a nominal elongation at break of 10.2%, a tensile strength of 73.5 MPa in the extrusion direction, and a nominal elongation at break of 5.2% and a tensile strength of 54.4 MPa in the transverse direction.

The haze of the film was 5.51%.

Claims (45)

1. Poly(meth)acrylimide film for use in a counterfeiting prevention label, where the poly(meth)acrylimide film contains from 30.0 to 92.5 wt. % poly(meth)acrylimide; from 2.5 to 40.0 wt. % of one or more impact modifiers; from 0.0 to 30.0 wt. % polyalkyl(meth)acrylate; from 5.0 to 40.0 wt. % of one or more inorganic fillers; from 0.0 to 5.0 wt. % of one or more UV absorbers and from 0.0 to 5.0 wt. % of one or more UV stabilizers, based on the weight of the poly(meth)acrylimide film; where poly(meth)acrylimide contains at least 50 wt. %, preferably at least 60 wt. %, most preferably at least 70 wt. % based on the weight of poly(meth)acrylimide repeating units of formula (I),

wherein R ¹ and R ² are independently selected from hydrogen and a methyl group, preferably R ¹ and R ² are a methyl group, and R ³ is hydrogen or a C ₁ -C ₄ alkyl group, preferably a methyl group; and while the total content of poly(meth)acrylimide, polyalkyl(meth)acrylate and impact strength modifying additive is from 60.0 to 95.0 wt. % based on the weight of the poly(meth)acrylimide film; and wherein content in weight. The % of one or more impact modifiers, n _im , in a poly(meth)acrylimide film is described by the following relationship: 0.5 × n _f ≤ n _im ≤ 1.8 × n _f , wherein n _f is the content in weight. % of one or more inorganic fillers in the poly(meth)acrylimide film. 2. The poly(meth)acrylimide film according to claim 1, wherein the poly(meth)acrylimide film has a thickness of 15.0 to 120.0 µm, and a nominal elongation at break of 3.0 to 30%, measured according to DIN EN ISO 527-3/2/100 (2003) using a thin film of 50.0 µm, and tensile stress from 20.0 to 70.0 MPa, measured according to DIN EN ISO 527-3/2/100 (2003) using a thin film with a thickness of 50.0 µm. 3. The poly(meth)acrylimide film according to claim 1 or 2, wherein the poly(meth)acrylimide film has a tear propagation resistance measured in accordance with ASTM D1938 (2014) using a 50.0 µm thick thin film of between 0, 01 to 1.50 N/mm. 4. Poly(meth)acrylimide film according to any one of paragraphs. 1-3, where the content is in weight. The % of one or more impact modifiers, n _im , in a poly(meth)acrylimide film is described by the following relationship: 0.6 × n _f ≤ n _im ≤ 1.5 × n _f , wherein n _f is the content in weight. % of one or more inorganic fillers in the poly(meth)acrylimide film. 5. Poly(meth)acrylimide film according to any one of paragraphs. 1-4, characterized in that one or more inorganic fillers are selected from titanium dioxide, silicon dioxide, zinc oxide, zinc sulfide, barium sulfate, carbon black, aluminum trihydroxide or calcium carbonate. 6. Poly(meth)acrylimide film according to any one of paragraphs. 1-5, characterized in that the poly(meth)acrylimide is characterized by an average molar mass Mw from 80,000 to 200,000 g/mol, preferably from 90,000 to 150,000 g/mol, determined using gel permeation chromatography using polymethyl methacrylate as a standard. 7. Label to prevent falsification, containing a poly(meth)acrylimide film according to any one of paragraphs. 1-6. 8. The anti-counterfeiting label according to claim 7, wherein the anti-counterfeiting label comprises at least the following layers in that order: a) a layer consisting of a poly(meth)acrylimide film according to any one of paragraphs. 1-6, preferably characterized by a thickness of 40.0 to 60.0 μm; b) an adhesive layer, preferably characterized by a thickness of 20.0 to 30.0 µm; c) a separating layer, preferably having a thickness of 0.6 to 0.8 µm; and d) a substrate layer, preferably having a thickness of 30.0 to 50.0 µm; and/or the counterfeit prevention label is characterized by a thickness of 50.0 to 300.0 µm. 9. Laminate material for manufacturing a counterfeiting label according to claim 7 or 8, wherein the laminate contains at least the following layers: a) a backing layer, preferably having a tear resistance of 50 to 500 N measured in accordance with ASTM D1004 (2013) using a 50.0 µm thin film; and b) a layer consisting of a poly(meth)acrylimide film according to any one of paragraphs. 1-6. 10. The laminate according to claim 9, wherein the backing layer essentially consists of a polymeric material selected from the group consisting of polyethylene, polypropylene and polyethylene terephthalate, preferably biaxially oriented polypropylene or biaxially oriented polyethylene terephthalate. 11. A method for manufacturing a laminate according to claim 9 or 10, wherein the method includes at least the following steps: i) obtaining a poly(meth)acrylimide film according to any one of paragraphs. 1-6 using an extruder to form a poly(meth)acrylimide film; and ii) bonding the backing layer to the poly(meth)acrylimide film from step i) downstream of the extruder. 12. The method of claim 11, wherein the laminate obtained in step ii) is passed between a plurality of rolls, wherein at least one roll facing the poly(meth)acrylimide film is a chill roll. 13. A method for manufacturing a counterfeit prevention label according to claim 7 or 8, wherein the method includes at least the following steps: i) obtaining a poly(meth)acrylimide film according to any one of paragraphs. 1-6 using an extruder; ii) bonding the backing layer to the poly(meth)acrylimide film from step i) downstream of the extruder to form a laminate; iii) bonding an adhesive layer, optionally a release layer and a backing layer to the laminate from step ii), whereby a label blank is obtained; and iv) notching the label blank obtained in step iii) and removing the resulting residual matrix, thereby obtaining a plurality of individual self-adhesive labels on the backing layer to prevent counterfeiting. 14. The use of a label to prevent falsification according to any one of paragraphs. 7, 8 for making chip cards, documents, counterfeiting prevention labels, electronic product identification labels, hidden car labels, document seals or price tags.

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