Blocked mdo label film

Abstract

The invention relates to a monoaxially stretched film (1) for a label, comprising at least one inner layer (5). The film (1) has at least one outer layer (2) on each side. At least one intermediate layer (4) is arranged between at least one inner layer (5) and at least one outer layer (2). The film (1) has at least one functional layer (3), the at least one functional layer (3) comprising a mixture of at least two polyethylenes of different densities. The higher-density polyethylene has a density of more than 0.94 g / cm3 in at least one of the functional layers (3), and the lower-density polyethylene has a density of less than 0.94 g / cm3 in at least one of the functional layers (3).

Description

[0001] Blocked MDO label film

[0002] Description

[0003] The invention relates to a monoaxially stretched film for a label, with at least one inner layer, wherein the film has at least one outer layer on each side and at least one middle layer is arranged between at least one inner layer and at least one outer layer.

[0004] It is common practice to affix labels to the surface of items such as bottles or containers made of polymers or glass to decorate them and / or to present information about the product being sold. Such information may include the contents of the item, a trade name, or a logo.

[0005] Plastic label films have long been known in the art. Originally, films made of mono- or biaxially oriented polyesters or machine-oriented polypropylenes were used. These label films are typically printed and coated with an adhesive layer. A release liner, consisting of a non-stick film or paper, is applied to the adhesive layer for protection.

[0006] The actual labeling of substrates is done mechanically by guiding the label around an edge of the backing material, causing the label to detach from the backing material and be transferred to the substrate. This requires sufficient rigidity of the label material.

[0007] On the other hand, the label must easily conform to the contours of the substrate, even if it is curved or bent, and must adapt to flexible substrates such as squeezable plastic bottles during the actual deformation process. Further requirements include transparency, gloss, printability of the surface, and, of course, low material and manufacturing costs for the label film.

[0008] One disadvantage of the known films is that the sufficient stiffness of the label sections required for automatic labeling systems can only be achieved through additionally stiffened plastic materials such as polypropylene or polyethylene terephthalate.

[0009] Nowadays, most adaptable polymeric label top films are made from low-density polyethylene (LDPE) with a small addition of high-density polyethylene (HDPE) or polypropylene (PP) in the formulation, in thicknesses between 80 pm and 100 pm, using blown or cast film processes.

[0010] Higher HDPE content would be desirable in terms of stiffness to enable downgauging, i.e., the use of thinner films. However, the anisotropy of HDPE-based films causes problems when cutting labels. Furthermore, bubble stability issues can arise in the blown film process if the HDPE content is too high.

[0011] EP 2 578 395 A1 describes a transparent, rigid and directly printable label film material with a core layer comprising a polyolefin-based layer with an MFI (190 °C / 2.16 kg) of less than 5 g / 10 min and a density of less than 0.950 kg / dm³ 3 comprises a sandwich-like structure between two stiffer layers based on a polyolefin with a tensile modulus according to DIN ISO 527-3 of at least 600 MPa and a density of at least 0.95 kg / dm³ 3 and two printable skin layers made of low-density polyethylene with a density of at least 0.923 kg / dm² 3 , wherein the ratio of the thickness of the innermost core layer to the thickness of each of the sandwich layers is in the range of 10 : 1 to 1 : 1 and the core layers together make up at least 50% of the total film thickness.

[0012] EP 2 860 031 B1 discloses a multilayer film suitable for labels, stretched in the machine direction, comprising a core layer and two outer layers sandwiched around the core layer, wherein the core layer is a polyethylene with a density between 926 kg / m³ 3 up to 950 kg / m² 3 includes and the two outer layers are an HDPE with a density of more than 940 kg / m³ 3 up to 970 kg / m² 3 include.

[0013] As part of its "Green Deal," the European Union aims to reduce the landfilling of plastic waste. By 2030, 55% of plastic packaging waste is to be recycled, and a significant portion of packaging mass is to be saved. This presents entirely new challenges for the production and assembly of labels.

[0014] To meet challenges such as recycling, packaging design must become increasingly sustainable. This leads to plastic packaging where both the substrate and the labels are consistently and systematically designed using a mono-material approach.

[0015] Furthermore, simultaneously reducing the thickness of the label film and thus the total plastic mass can make a significant contribution. The challenge lies in achieving the previously known mechanical and optical parameters with just one recyclable mono-material construction and, at the same time, a significantly thinner label film.

[0016] The object of the present invention is to provide a film for a label that meets the requirements of a mono-material construction and can guarantee good mechanical properties. To this end, the film should be particularly stiff and have a thickness of less than 60 µm. Furthermore, the film should be easily recyclable. The film should be inexpensive to print on and of excellent quality. The film should be harmless to health and environmentally sustainable.

[0017] This objective is achieved according to the invention by a film for a label according to the main claim. Preferred embodiments can be found in the dependent claims, the description, and the drawing.

[0018] According to the invention, the film has at least one functional layer, wherein the at least one functional layer comprises a mixture of at least two polyethylenes of different densities, wherein the higher-density polyethylene in at least one of the functional layers has a density of more than 0.94 g / cm³ 3 exhibits and the low-density polyethylene in at least one of the functional layers has a density of less than 0.94 g / cm³ 3 exhibits.

[0019] For example, the density of the higher-density polyethylene in at least one of the functional layers is greater by a factor than the lower-density polyethylene in at least one of the functional layers, wherein the value of the factor is more than 1.002, preferably more than 1.005, in particular more than 1.008 and / or less than 1.20, preferably less than 1.15, in particular less than 1.10.

[0020] In one embodiment of the invention, at least one functional layer is arranged between the inner layer and a middle layer. The functional layer serves to provide the film with sufficiently high stiffness, particularly for the application process of the label to a substrate.

[0021] For example, at least one functional layer is arranged between a middle layer and an outer layer. Depending on the substrate, a functional layer positioned further out in the film can achieve advantageous and application-specific stiffness.

[0022] In a further embodiment of the invention, at least one functional layer is arranged between an inner layer and a middle layer, as well as at least one functional layer between a middle layer and an outer layer. The plurality of functional layers, as well as their distribution throughout the film structure, allows for the creation of a particularly rigid film suitable for label applications while simultaneously reducing the film thickness.

[0023] For example, the proportion of higher density polyethylene in at least one of the functional layers in the mixture is more than 10 wt.% and less than 60 wt.%.

[0024] In a further embodiment of the invention, the proportion of higher density polyethylene in at least one of the functional layers in the mixture is more than 20 wt.%, in particular more than 25 wt.% and less than 50 wt.%, in particular less than 40 wt.%.

[0025] For example, the proportion of low-density polyethylene in at least one of the functional layers in the mixture is more than 40 wt.% and less than 90 wt.%.

[0026] In an alternative embodiment of the invention, the proportion of low-density polyethylene in at least one of the functional layers in the mixture is more than 50 wt.%, in particular more than 60 wt.% and less than 85 wt.%, in particular less than 75 wt.%.

[0027] The flow behavior of polyolefins is described using the melt flow rate according to ISO 1133-1, typically at a temperature of 190 °C for polyethylene and 230 °C for polypropylene, under a load of 2.16 kg, 5 kg, or 21.6 kg. A higher melt flow index correlates with a lower average molecular weight of the polymer. Simultaneously, the higher the melt flow index of a polymer, the lower its melt viscosity, which is advantageous for high extrusion output. Conversely, polymers with a high molecular weight, i.e., a low melt flow index, are advantageous with regard to mechanical stability, particularly tensile strength and toughness.

[0028] For example, the higher density polyethylene in at least one of the functional layers is made of HDPE with a density greater than 0.942 g / cm³. 3 , preferably more than 0.944 g / cm³ 3 is and / or less than 0.97 g / cm²3 , preferably less than 0.965 g / cm³ 3 is and / or its melting flow rate (at 190 °C at 21.6 kg) according to ISO 1133-1 is more than 5 g / 10 min, preferably more than 10 g / 10 min and / or is less than 25 g / 10 min, preferably less than 20 g / 10 min.

[0029] In one variant of the invention, the HDPE has a melt flow rate according to ISO 1133-1 of more than 1.0 g / 10 min, preferably more than 1.25 g / 10 min, in particular more than 1.5 g / 10 min and / or less than 3.0 g / 10 min, preferably less than 2.0 g / 10 min, in particular less than 1.75 g / 10 min at 190 °C and 5 kg in at least one of the functional layers.

[0030] For example, the HDPE in at least one of its functional layers exhibits a tensile elasticity of more than 880 MPa, a tensile strength of more than 20 MPa, and a crystallite melting point of more than 129 °C. These specific physical parameters result in a film that can advantageously fulfill the given task. Advantageously, the low-density polyethylene in at least one of its functional layers is composed of a polyethylene with a density greater than 0.91 g / cm³. 3 , preferably more than 0.92 g / cm³ 3 is and / or less than 0.95 g / cm² 3 , preferably less than 0.94 g / cm³ 3 is and / or its melting flow rate (at 190 °C for 5 kg) according to ISO 1133-1 is more than 0.1 g / 10 min, preferably more than 1.0 g / 10 min and / or is less than 5.0 g / 10 min, preferably less than 3.0 g / 10 min.

[0031] For example, the low-density polyethylene in at least one of the functional layers is formed from a bimodal polyethylene, preferably from a bimodal terpolymer, in particular from a bimodal ethylene / 1-butene / Ce-Ci2-alpha-olefin terpolymer. The combination of polymer chains with low molecular weight and high density, as well as those with high molecular weight and low density, results in a combination of stiffness and flexibility in the polyethylene in at least one of the functional layers. This enables an optimal balance between strength, impact resistance, in particular high stiffness, and processability of the resulting polyethylene in at least one of the functional layers.

[0032] The outer layer of the film forms the label's skin, which can be attractively printed and influences the consumer's tactile experience. In one embodiment of the invention, the outer layer contains HDPE with a density greater than 0.942 g / cm³. 3 , preferably more than 0.944 g / cm³ 3 is and / or less than 0.97 g / cm² 3 , preferably less than 0.965 g / cm³ 3 is and / or its melting flow rate (at 190 °C at 21.6 kg) according to ISO 1133-1 is more than 5 g / 10 min, preferably more than 10 g / 10 min and / or is less than 25 g / 10 min, preferably less than 20 g / 10 min.

[0033] For example, the HDPE in at least one outer layer has a melt flow rate according to ISO 1133-1 of more than 1.0 g / 10 min, preferably more than 1.25 g / 10 min, in particular more than 1.5 g / 10 min and / or less than 3.0 g / 10 min, preferably less than 2.0 g / 10 min, in particular less than 1.75 g / 10 min at 190 °C and 5 kg.

[0034] In one embodiment of the invention, the HDPE in at least one outer layer exhibits a tensile elasticity of more than 880 MPa, a tensile strength of more than 20 MPa, and a crystallite melting point of more than 129 °C. These special parameters result in a film that is particularly well-suited for printing and gives the label a pleasant feel.

[0035] To improve the adhesion of a high-quality print, at least one outer layer of the film is made from a high proportion of HDPE, which may also contain additives as well as process and processing aids.

[0036] For example, the HDPE of at least one outer layer has a medium molecular weight and a particularly narrow molecular weight distribution, resulting in good bubble stability and processability. Furthermore, this outer layer exhibits excellent tensile strength and good elongation at break with a low tendency to fibrillate. This allows the film to be printed with exceptional precision and high quality for labels, as the web tension can be precisely maintained even at high web speeds while maintaining a particularly thin film.

[0037] In one embodiment of the invention, the proportion of HDPE in at least one outer layer is more than 40 wt.%, preferably more than 60 wt.%, in particular more than 80 wt.% and / or less than 95 wt.%, preferably less than 90 wt.%, in particular less than 85 wt.%. The proportion of higher-density polyethylene gives the film excellent stiffness and heat resistance. In another embodiment of the invention, the proportion of a further polyethylene in at least one outer layer is more than 5 wt.%, preferably more than 10 wt.%, in particular more than 15 wt.% and / or less than 60 wt.%, preferably less than 40 wt.%, in particular less than 20 wt.%. The proportion of this polyethylene ensures favorable toughness of the film.

[0038] For example, the additional polyethylene in at least one outer layer has a density of more than 0.91 g / cm³. 3 , preferably of more than 0.92 g / cm³ 3is and / or less than 0.95 g / cm² 3 , preferably of less than 0.94 g / cm³ 3 on and / or its melting flow rate (at 190 °C at 5 kg) is, according to ISO 1133-1, more than 0.1 g / 10 min, preferably more than 1.0 g / 10 min and / or less than 5.0 g / 10 min, preferably less than 3.0 g / 10 min.

[0039] For example, the polyethylene in at least one outer layer is formed from a bimodal polyethylene, preferably from a bimodal terpolymer, in particular from a bimodal ethylene / 1-butene / Ce-Ci2-alpha-olefin terpolymer. The combination of polymer chains with low molecular weight and high density, as well as those with high molecular weight and low density, results in a combination of stiffness and flexibility in the polyethylene in at least one of the outer layers. This enables an optimal balance between strength, impact resistance, stiffness, and processability of the resulting polyethylene in at least one outer layer.

[0040] In one embodiment of the invention, the at least one middle layer is formed from a bimodal polyethylene, preferably from a bimodal terpolymer, in particular from a bimodal ethylene / 1-butene / C6-C12-alpha-olefin terpolymer. The combination of polymer chains with low molecular weight and high density as well as those with high molecular weight and low density results in a combination of stiffness and flexibility in at least one middle layer.

[0041] For example, bimodal polyethylene has a density greater than 0.91 g / cm³ in at least one middle layer. 3 , preferably more than 0.92 g / cm³ 3 on and / or less than 0.95 g / cm² 3 , preferably less than 0.94 g / cm³ 3on and / or its melting flow rate (at 190 °C at 5 kg) according to ISO 1133-1 is more than 0.1 g / 10 min, preferably more than 1.0 g / 10 min and / or is less than 5.0 g / 10 min, preferably less than 3.0 g / 10 min.

[0042] In one embodiment of the invention, the at least one inner layer is designed as a blocking layer and comprises at least one linear low-density polyethylene with a density of less than 0.90 g / cm³. 3 on.

[0043] The formation of a blocked film results in a label with a multi-layered structure, whereby the film can be stretched, enabling excellent film properties to be achieved even with a particularly thin film structure.

[0044] For example, an inner layer is formed from a polyethylene whose density according to ISO 1183-1 is more than 0.85 g / cm³. 3 , preferably more than 0.86 g / cm³ 3 is and / or less than 0.905 g / cm³3 , preferably less than 0.89 g / cm³ 3 is and / or its melting flow rate (at 190 °C for 5 kg) according to ISO 1133-1 is more than 0.1 g / 10 min, preferably more than 0.5 g / 10 min and / or is less than 3.0 g / 10 min, preferably less than 2.0 g / 10 min.

[0045] In one embodiment of the invention, the proportion of LLDPE in at least one inner layer is more than 10 wt.%, preferably more than 20 wt.%, particularly more than 25 wt.% and / or less than 50 wt.%, preferably less than 40 wt.%, particularly less than 35 wt.%. The proportion of linear low-density polyethylene gives the inner layer excellent blocking properties.

[0046] In a further embodiment of the invention, the proportion of a further polyethylene in at least one inner layer is more than 50 wt.%, preferably more than 60 wt.%, in particular more than 65 wt.% and / or less than 90 wt.%, preferably less than 80 wt.%, in particular less than 75 wt.%.

[0047] For example, the additional polyethylene in at least one inner layer has a density of more than 0.91 g / cm³. 3 , preferably of more than 0.92 g / cm³ 3 is and / or less than 0.95 g / cm² 3 , preferably of less than 0.94 g / cm³ 3 on and / or its melting flow rate (at 190 °C at 5 kg) is, according to ISO 1133-1, more than 0.1 g / 10 min, preferably more than 1.0 g / 10 min and / or less than 5.0 g / 10 min, preferably less than 3.0 g / 10 min.

[0048] In one variant of the invention, the at least one inner layer may additionally contain a proportion of additives as well as process and processing aids.

[0049] For example, the further polyethylene in at least one inner layer is formed from a bimodal polyethylene, preferably from a bimodal terpolymer, in particular from a bimodal ethylene / 1-butene / Ce-Ci2-alpha-olefin terpolymer.

[0050] In one variant, the film consists of an outer layer, two middle layers, a functional layer, and an inner layer. The simplest variant of the invention is a five-layer film. For example, the inner layer is designed as a blocking layer, resulting in a ten-layer film for a label.

[0051] In a more complex version of the invention, the film consists of eighteen layers in a block configuration. Two outer layers adjoin a functional layer, followed by three middle layers. A further functional layer is positioned between the middle layers and two inner layers. The four functional layers together form an exceptionally stiff and tough film, ideally suited for label production and automated label application. The multi-layered structure, the stretched design, and the particularly thin profile give the film a level of environmental compatibility previously unmatched by known labels.

[0052] In principle, further films are included within the scope of the invention between the five-layer and the eighteen-layer variants, whereby the mechanical properties can be improved with an increasing number of layers, in particular the number of layers of the functional layer.

[0053] For example, the multi-layered structure of the film is symmetrical.

[0054] To achieve the advantageous mechanical properties, the film is ideally stretched monoaxially in the machine direction by more than a factor of 2.0, preferably by more than a factor of 3.0, in particular by more than a factor of 4.0 and / or stretched by less than a factor of 7.0, preferably by less than a factor of 6.5, in particular by less than a factor of 6.0.

[0055] The thickness of the film was determined according to DIN 53370 and is given as an average value. For example, the film has a thickness of less than 80 pm, preferably less than 70 pm, particularly less than 60 pm and / or more than 20 pm, preferably more than 30 pm, particularly more than 40 pm.

[0056] In one variant of the invention, the film has a thickness of 49 pm and thus fulfills the stated task extremely advantageously from the point of view of environmental protection, in particular reduction of packaging mass.

[0057] For example, a print is placed directly on an outer layer of the film.

[0058] Flexographic printing is a commonly used method for printing on film. It is a direct relief printing process, also known as a roll-to-roll rotary printing process. The flexible printing plates, made of photopolymer or rubber, are used in combination with low-viscosity inks. The raised areas of the printing plate bear the image. The advantages lie in its cost-effectiveness, achieved through the use of large printing widths and high printing speeds, as well as the availability of inexpensive inks. The printing tools consist primarily of photopolymer printing plates and / or laser-engraved elastomer sleeves. Flexographic printing is well-suited for producing large print runs economically.

[0059] Preferably, the print is applied directly to an outer layer of the film. The print can be located on the side facing away from the packaged goods or, in the sense of reverse printing, between the film and the substrate. Furthermore, the print can be designed as a motif. In the context of film, the term "motif" refers to the thematic design element of a print. Optionally, manufacturer-identifying motifs can also be included within the scope of the print. Preferably, the print is applied to at least the outermost layer of the film using a flexographic printing process, whereby all common printing processes are fundamentally suitable and expressly included in the invention.

[0060] To achieve recyclability and thus also sorting in modern waste separation plants, such as the float-sink method, the density of the film for a label is less than 0.99 g / cm³.3 , preferably less than 0.97 g / cm³ 3 , especially less than 0.95 g / cm³ 3 and / or more than 0.60 g / cm³ 3 , preferably more than 0.70 g / cm³ 3 , especially more than 0.80 g / cm² 3 .

[0061] The haze value is a measure of the opacity of transparent films. The method for measuring the haze value is described in the standard ASTM D 1003. Advantageously, the film has a haze of less than 15%, preferably less than 12.5%, and particularly less than 10%.

[0062] In one variant, the film has a bending stiffness in the machine direction according to ISO 2493 of more than 150 mN, preferably more than 175 mN, in particular more than 200 mN.

[0063] For example, the film has a bending stiffness transverse to the machine direction according to ISO 2493 of more than 170 mN, preferably more than 195 mN, in particular more than 220 mN.

[0064] Thus, the film according to the invention fulfills the stated task with regard to sufficient stiffness, so that the film can be applied to substrates in modern, automated labeling systems.

[0065] The advantageous mechanical properties are currently only known from films based on a material mix of different thermoplastics. The monomaterial construction according to the invention is characterized by complete and simple recyclability.

[0066] For example, the additional outer layer can be placed on the side of the film facing away from the print and / or visible from the outside. The matte surface gives the film an attractive appearance.

[0067] Further advantages and features of the invention will become apparent from the description of an exemplary embodiment with reference to a drawing and from the drawing itself.

[0068] This shows

[0069] Fig. 1 shows a schematic structure of the label according to the invention,

[0070] Fig. 2 shows another embodiment of the label according to the invention,

[0071] Fig. 3 shows a third embodiment of the label according to the invention.

[0072] Figure 1 shows a schematic structure of film 1 for a label in a blocked version. Film 1 is blocked to the inner layer 5 of the unblocked film variant 6 to form an eighteen-layer structure.

[0073] The film 1 has a symmetrical structure and features two outer layers 2 on each side, each directly bonded to a functional layer 3. Three very thin middle layers 4 are arranged against each of these functional layers 3, followed directly by two more functional layers 3, and each of these is capped by an inner layer 5 as a blocking layer. The film 1 is monoaxially stretched by a factor of 5.4 in the machine direction and has a thickness of 50 pm according to DIN 53370. The film 1 achieves a flexural stiffness of 205 mN in MD and a flexural stiffness of 224 mN in CD. The density of the film 1 for a label is 0.932 g / cm³. 3 and has a haze value of 9.7% according to ASTM D 1003.

[0074] Before stretching, the two outer layers 2 each have a thickness of 20 pm, the functional layers 3 each have a thickness of 20 pm, the middle layers 4 each have a thickness of 9 pm and the inner layer 5 has a thickness of 8 pm.

[0075] The outer layers 2 of the film 1 consist of a proportion of additives (a highly transparent anti-blocking and IR filter masterbatch based on silica in PE carrier resin and / or a processing aid to level the flowability of the melt) of 2 wt.%, made of an HDPE (density 0.946 g / cm³). 3 and melt flow rate (at 190 °C at 5 kg) according to ISO 1133 1.6 g / 10 min) with a proportion of 83 wt.% and another polyethylene (density 0.937 g / cm³) 3 and melting flow rate (at 190 °C at 5 kg) according to ISO 1133 2.0 g / 10 min) with a proportion of 15 wt.%.

[0076] The functional layers 3 consist of a mixture of two polyethylenes, with the proportion of higher-density polyethylene being 30 wt.% and the proportion of lower-density polyethylene being 70 wt.% in this embodiment. In the illustrated embodiment, the higher-density polyethylene of the functional layers 3 is an HDPE with a density of 0.946 g / cm³. 3 and whose melt flow rate (at 190 °C for 5 kg) according to ISO 1133 is 1.6 g / 10 min. The low-density polyethylene of the functional layers 3 is implemented as a bimodal ethylene / 1-butene / C6-Ci2-alpha-olefin terpolymer, whose density is 0.937 g / cm³. 3 and whose melt flow rate (at 190 °C for 5 kg) according to ISO 1133 is 2 g / 10 min. The middle layers 4 are made of a bimodal ethylene / 1-butene / Ce-Ci2-alpha-olefin terpolymer, whose density is 0.937 g / cm³. 3 and whose melting flow rate (at 190 °C at 5 kg) according to ISO 1133 is 2 g / 10 min.

[0077] The inner layers 5 of the film 1 consist of an LLDPE (density 0.87 g / cm³). 3 and melt flow rate (at 190 °C at 5 kg) according to ISO 1133 1.0 g / 10 min) with a proportion of 30 wt.% and another polyethylene (density 0.937 g / cm³) 3 and melting flow rate (at 190 °C at 5 kg) according to ISO 1133 2.0 g / 10 min) with a proportion of 70 wt.%.

[0078] Due to the special composition of the polymeric raw materials and the sophisticated arrangement of the functional layers 3 as well as the stretching in the machine direction, the film 1 achieves a previously unattained stiffness with a particularly thin design of significantly less than 60 pm, so that the film 1 can be applied excellently as a label to substrates in modern, automated labeling systems and, due to the particularly thin design, at the same time significantly reduces the mass of packaging material.

[0079] Figure 2 shows another embodiment of foil 1 for a label. The embodiment is essentially the same as the one in Figure 1, so only the differences are listed below.

[0080] Before stretching, the two outer layers 2 each have a thickness of 22 pm, the functional layers 3 each have a thickness of 22 pm, the middle layers 4 each have a thickness of 9 pm, and the inner layers 5 each have a thickness of 10 pm. The film 1 has two inner layers 5 as blocking layers, but only one functional layer 3 between the middle layers 4 and the inner layers 5. Figure 3 shows a third embodiment of the film 1 for a label, which corresponds to the layer structure of Figure 2, but has differences in the layer thicknesses.

[0081] The film 1 has a symmetrical structure, and in the unblocked film variant 6, the top side corresponds to the outer surface when viewed from above. Before stretching, the outermost layer 2 has a thickness of 19.5 pm, and the innermost layer 2 has a thickness of 18.5 pm. The functional layers 3 each have a thickness of 14.75 pm, and the middle layers each have a thickness of 6.5 pm. The innermost layer 5, adjacent to the functional layer 3, has a thickness of 19 pm in this configuration. The innermost layer 5 has a thickness of 29 pm. The film 1 is stretched monoaxially in the machine direction by a factor of 5.47 and has a thickness of 49.4 pm according to DIN 53370.

Claims

Patent claims 1. Monoaxially stretched film (1) for a label, with at least one inner layer (5), wherein the film (1) has at least one outer layer (2) on each side and at least one middle layer (4) is arranged between at least one inner layer (5) and at least one outer layer (2), characterized in that the film (1) has at least one functional layer (3), wherein the at least one functional layer (3) comprises a mixture of at least two polyethylenes of different densities, wherein the higher-density polyethylene in at least one of the functional layers (3) has a density of more than 0.94 g / cm³ 3 exhibits and the low-density polyethylene in at least one of the functional layers (3) has a density of less than 0.94 g / cm³ 3 2. Foil according to claim 1, characterized in that at least one The functional layer (3) is arranged between the inner layer (5) and a middle layer (4).

3. Film according to claim 1 or 2, characterized in that at least one functional layer (3) is arranged between a middle layer (4) and an outer layer (2).

4. Film according to one of claims 1 to 3, characterized in that the proportion of higher density polyethylene in at least one of the functional layers (3) is more than 10 wt.% and less than 60 wt.%.

5. Film according to one of claims 1 to 4, characterized in that the proportion of low-density polyethylene in at least one of the functional layers (3) is more than 40 wt.% and less than 90 wt.%.

6. Film according to one of claims 1 to 5, characterized in that the density of the higher-density polyethylene in at least one of the functional layers (3) is greater by a factor than the lower-density polyethylene in at least one of the functional layers (3), wherein the value of the factor is more than 1.002, preferably more than 1.005, in particular more than 1.008 and / or less than 1.20, preferably less than 1.15, in particular less than 1.

10.

7. Film according to one of claims 1 to 6, characterized in that the at least one middle layer (4) is formed from a bimodal polyethylene, preferably from a bimodal terpolymer, in particular from a bimodal ethylene / 1-butene / C6-C12-alpha-olefin terpolymer.

8. Film according to one of claims 1 to 7, characterized in that the at least one inner layer (5) is designed as a blocking layer and comprises at least one linear low-density polyethylene with a density of less than 0.90 g / cm³ 3 exhibits.

9. Film according to one of claims 1 to 8, characterized in that the film (1 ) is stretched monoaxially in the machine direction by more than a factor of 2.0, preferably by more than a factor of 3.0, in particular by more than a factor of 4.0 and / or is stretched by less than a factor of 7.0, preferably by less than a factor of 6.5, in particular by less than a factor of 6.

0.

10. Foil according to one of claims 1 to 9, characterized in that the foil (1 ) has a thickness of less than 80 pm, preferably less than 70 pm, in particular less than 60 pm and / or more than 20 pm, preferably more than 30 pm, in particular more than 40 pm.

11. Film according to one of claims 1 to 10, characterized in that a print is arranged directly on an outer layer (2) of the film (1 ).

12. Film according to one of claims 1 to 11, characterized in that the film (1) is multilayered, wherein the multilayered structure of the film (1) is symmetrical.

13. Film according to one of claims 1 to 12, characterized in that the density of the film (1 ) is less than 0.99 g / cm³ 3 , preferably less than 0.97 g / cm³ 3 , especially less than 0.95 g / cm³ 3 is and / or more than 0.60 g / cm² 3 , preferably more than 0.70 g / cm³ 3 , especially more than 0.80 g / cm² 3 amounts.

14. Film according to one of claims 1 to 13, characterized in that the film (1 ) has a turbidity according to ASTM D 1003 of less than 15%, preferably of less than 12.5%, in particular of less than 10%.

15. Film according to one of claims 1 to 14, characterized in that the film (1 ) has a bending stiffness in the machine direction according to ISO 2493 of more than 150 mN, preferably of more than 175 mN, in particular of more than 200 mN and a bending stiffness transverse to the machine direction according to ISO 2493 of more than 170 mN, preferably of more than 195 mN, in particular of more than 220 mN.

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