Elastic film

Abstract

The invention relates to an elastic film (1) having at least one core layer (3) based on styrene block copolymers, the at least one core layer (3) being arranged between at least two cover layers (2). The cover layers (2) have elastic properties without activation, the film (1) having a force of less than 3.75 N when stretched by 160% in a first loading cycle. For this purpose, a film strip for the loading cycle has a width of 25 mm in the MD direction and the film strip is fastened, at a CD distance of 25 mm, between grippers of a testing device and the film strip is stretched in CD at a speed of 254 mm / min.

Description

[0001] Elastic film

[0002] Description

[0003] The invention relates to an elastic film with at least one core layer based on styrene block copolymers, wherein the at least one core layer is arranged between at least two cover layers.

[0004] Elastic, stretchable materials are used in diapers to ensure an optimal fit and leakage protection. These materials are used in various forms: firstly, as a diaper waistband, also known as a "waistband," and secondly, as an elastic closure element called a "back ear" in baby diapers. They are also used as a belt in pull-up diapers.

[0005] To improve wearing comfort, these elements contain elastic components that adapt to the individual body shape thanks to their resilience. To ensure a pleasant feel against the skin, these elastic components, often in the form of films, are combined with textile materials such as nonwovens or fleeces.

[0006] EP 2 024 178 B1 describes a method for producing an elastically stretchable laminate with three layers. The laminate comprises an elastic film and two layers of non-elastic nonwoven fabric. In one variant, a crepe nonwoven fabric is used. A first elastic laminate is bonded to a non-elastic nonwoven layer in a stretched state.

[0007] The elasticity of the films is usually finalized in an activation process. This process can include steps such as heating the films to a specific temperature and aligning the molecules within the material to prepare them for activation. Furthermore, the prepared films are stretched mechanically or thermally. This can be achieved by applying tensile forces during the manufacturing process or by subsequent heating and stretching of the films. During stretching, the molecules in the material are rearranged, giving the film its elasticity.

[0008] EP 1 316 418 B1 discloses a monoaxially elastic laminate film with a core layer made of a thermoplastic elastomer and at least one skin layer coextruded together with the core layer, wherein the skin layer consists of a thermoplastic polymer with a brittle, strengthened molecular structure which can only stretch slightly under the application of a tensile force and can tear seamlessly when a predetermined tearing force is exceeded.

[0009] US 2018 / 0264163 A1 and WO 2018 169 656 A1 disclose thermoplastic multilayer films and laminates and articles comprising these films, wherein the film comprises at least one inner layer and at least two outer layers, the inner layer comprising a polymer composition comprising approximately 55% to approximately 95% of one or more non-hydrogenated styrene block copolymers, olefin block copolymers or combinations thereof; and each outer layer comprising at least 20% polypropylene and having a thickness of approximately 5% to approximately 15% of the total film thickness, and wherein the film further exhibits a constant force propagation of approximately 20% or less.

[0010] EP 2 069 141 B1 describes an activatable stress-free composite laminate sheet comprising an activatable elastic laminate sheet having an elastic core layer and at least one outer layer which is less elastic than the core layer, and at least one pre-bonded staple fiber nonwoven sheet which is attached to one of the outer layers of the elastic laminate sheet, wherein the at least one staple fiber nonwoven sheet has an elongation at break of at least 100% in the transverse direction and the activatable elastic laminate sheet forms a substantially homogeneous microtextured surface when it is stretched in the transverse direction beyond the elastic limit of one or more outer layers during the first loading.

[0011] EP 3 228 291 B1 discloses an elastic film with an elastic film layer based on styrene block copolymer. The elastic film layer is formed without the addition of polystyrene from a first SIS and a second SIS, wherein the first SIS has a styrene content between 10 wt.% and 25 wt.% and a hardness of less than 45 Shore A, and the second SIS has a styrene content between 26 wt.% and 40 wt.% and a hardness of more than 45 Shore A, wherein the ratio of the first SIS to the second SIS is between 6:1 and 2:3, and wherein the elastic film layer is arranged between two non-elastic cover layers in a three-layer structure formed by co-extrusion.

[0012] EP 3 228 292 B1 discloses an elastic laminate for diaper closures with two opposing nonwoven layers forming the outer surfaces and with strips of elastic film running in a direction of tension and bonded between the nonwoven layers by adhesive. The strips are bonded between the nonwoven layers under pretension, and in a relaxed state, the nonwoven layers are folded along the direction of tension by the restoring forces of the pretensioned strips.

[0013] Particularly in the case of elastic films with non-elastic outer layers, the films are activated in a way that irreversibly breaks down the outer layers. This creates uniformly arranged cracks in the outer layers, which, similar to crevasses in a glacier, extend down to the elastic inner layer of the film. People who come into contact with elastic films in hygiene products and who may be sensitive to the substances in the elastic inner layers of the films can experience skin irritation upon direct contact with these substances. This can lead to discomfort and negatively impact the user experience.

[0014] The object of the present invention is to provide an elastic film that is elastic without any broken surface layers. Furthermore, the elastic film should be able to meet the requirements of modern processing converters. The elastic film should be inexpensive to manufacture, suitable for lamination with nonwoven fabric, and printable with excellent quality. In addition, the laminated elastic film should exhibit pleasant tensile properties for users. The elastic film should be harmless to health and environmentally sustainable.

[0015] This problem is solved according to the invention by an elastic film with at least one core layer according to the main claim. Preferred embodiments can be found in the dependent claims, the subclaims, the description and the drawings.

[0016] According to the invention, the cover layers exhibit elastic properties without activation, wherein in a first load cycle the film exhibits a force of less than 3.75 N at an elongation of 160%, wherein a film strip of 25 mm width in the MD direction and the film strip is fixed at a CD distance of 25 mm between grippers of a test device and the film strip is stretched in CD at a speed of 254 mm / min.

[0017] In one embodiment of the invention, the elastic film is designed as a three-layer system, comprising a core layer and a surrounding outer layer. In an alternative embodiment of the invention, the elastic film, in particular the core layer and / or the outer layers, can also comprise multiple layers.

[0018] Styrene block copolymers are a class of copolymers composed of repeating units of styrene and one or more other monomers. They belong to the family of thermoplastic elastomers and are characterized by their block structure, in which styrene blocks alternate with other polymerizable units. Typically, styrene block copolymers consist of a hard styrene block and a soft block, often composed of butadiene or isoprene. By combining hard and soft blocks in their structure, they unite the properties of elastomers and thermoplastics. The hard styrene blocks provide strength, stiffness, and dimensional stability, while the soft blocks impart elasticity, flexibility, and toughness.

[0019] In addition to slight elasticity, the elastic film should also possess sufficient holding power. This can be ensured by the elastic film and any elastic laminate formed from it exhibiting largely elastic properties, allowing a significant portion of the energy expended during stretching to be recovered during contraction.

[0020] In the context of testing the elastic behavior of the elastic film, the terms "first load" and "second load" refer to different phases of the testing process during a tensile test.

[0021] When a tensile force is first applied to an elastic film, it deforms in response to the applied force. The initial response of the material to this force is called the "first loading." During this phase, the material typically behaves linearly elastically, meaning that the deformation is proportional to the applied force according to Hooke's Law. In this linear elastic range, the material returns to its original shape after the force is removed, exhibiting reversible deformation. The test speed for the tensile test of the elastic film is 254 mm / min, meaning that the sample is loaded at a rate of 254 millimeters per minute.

[0022] When the applied force exceeds a certain threshold, the material can enter a region of nonlinear behavior where the relationship between stress and strain deviates from Hooke's Law. In this region, the material may begin to exhibit plastic deformation or other forms of inelastic behavior. The force required to induce this nonlinear response is often referred to as the yield strength. Beyond this point, the material may remain plastically deformed until it eventually fractures.

[0023] In a hysteresis test in CD, a test piece of elastic film measuring 25 mm in MD and 100 mm in CD was cut. The prepared film piece was then stretched in CD with a chuck spacing of 25 mm and a test speed of 254 mm / min to a chuck spacing of 80 mm (160%) and then released back to a chuck spacing of 25 mm. This method is also described in EP 4 122 675 A1.

[0024] According to the invention, the cover layers exhibit elastic properties without activation. This is achieved, for example, by subjecting the film to a force of less than 3.75 N and more than 2.75 N at an elongation of 160% during a first loading cycle, wherein a 25 mm wide film strip is attached in the MD direction and the film strip is positioned at a CD spacing of 25 mm between grippers of a test device, and the film strip is stretched at CD at a speed of 254 mm / min. In a further embodiment of the invention, the film exhibits a force of more than 3.0 N and less than 3.5 N at an elongation of 160% during the first loading cycle, wherein a 25 mm wide film strip is attached in the MD direction and the film strip is positioned at a CD spacing of 25 mm between grippers of a test device, and the film strip is stretched at CD at a speed of 254 mm / min.

[0025] For example, during the second load cycle, which could correspond to the application of a hygiene product even in the laminated state of the film, the film exhibits a force of more than 0.4 N and less than 1.0 N at an elongation of 8%, where a film strip of 25 mm width in the MD direction and the film strip is attached at a CD distance of 25 mm between grippers of a test device and the film strip is stretched in CD at a speed of 254 mm / min.

[0026] In one embodiment of the invention, the film exhibits a force of more than 0.6 N and less than 0.8 N at an elongation of 8% during the second load cycle, wherein a film strip of 25 mm width in the MD direction and the film strip is fixed at a CD distance of 25 mm between grippers of a test device and the film strip is stretched in CD at a speed of 254 mm / min.

[0027] For example, the ratio of the force during the first loading cycle of the film at an elongation of 160% to the force during the second loading cycle at an elongation of 8% is greater than 5 and less than 8, preferably greater than 5.5 and less than 7.5, and in particular greater than 6 and less than 7.

[0028] Ideally, the ratio of force during the first loading cycle of the film at 160% elongation to force during the second loading cycle at 8% elongation perfectly reflects the requirements of a film processing converter and the feel when using finished disposable hygiene products. The elastic film thus functions ideally in processing converters and simultaneously offers a comfortable stretch during use thanks to its optimized CD elongation forces.

[0029] An elastic film with these particularly advantageous mechanical properties with regard to elongation and restoring force is achieved by the special selection of styrene block copolymers in the core layer, the selection of polyethylene components in the top layer and the design as a blown film without activation with at least one core layer surrounded by at least two thin top layers.

[0030] For example, the cover layers have a first polyethylene component and a second polyethylene component.

[0031] In one variant of the invention, the first polyethylene component is made of a PE-POP, wherein the proportion of PE-POP is between 10 and 25 wt.%.

[0032] Polyolefin plastomers (POPs) are a relatively new class of polymers. They are copolymers of ethylene and octene. POPs bridge the gap between conventional elastomers and thermoplastics, enabling even permanently damaged surface layers to remain elastic and exceptionally soft.

[0033] The Melt Flow Index (MFI) is a measurement that indicates the flowability of thermoplastic materials under standardized conditions. Specifically, the MFI is measured as the mass of the plastic material, in grams, that flows through a standardized die at a given temperature and load within a defined time. The unit is expressed in g / 10 min. The MFI is an important measure of the processability of plastics in various applications, as it provides information about the material's flow properties. The higher the MFI value, the better the plastic flows, and vice versa.

[0034] For example, the first polyethylene component exhibits an MFI (at 190 °C and at 2.16 kg) according to ASTM D1238 of more than 0.5 g / 10 min and of less than 5.5 g / 10 min.

[0035] In one variant of the invention, the first polyethylene component has a density of more than 0.86 g / cm³. 3and of less than 0.89 g / cm³ 3 on.

[0036] For example, the second polyethylene component is made of LLDPE, with the proportion of LLDPE being between 30 and 70 wt.%.

[0037] In one embodiment of the invention, the second polyethylene component has an MFI (at 190 °C and at 2.16 kg) according to ASTM D1238 of more than 1.0 g / 10 min and of less than 4.0 g / 10 min.

[0038] For example, the second polyethylene component has a density of more than 0.91 g / cm³. 3 and of less than 0.95 g / cm³ 3 on.

[0039] For example, the ratio of the density of the first polyethylene component to the second polyethylene component is greater than 0.9 and less than 1.0.

[0040] In one embodiment of the invention, the ratio of the MFIs of the first polyethylene component to the second polyethylene component is greater than 0.125 and less than 1.5. For example, the ratio of the proportion of the first polyethylene component to the second polyethylene component is greater than 0.2 and less than 0.8.

[0041] For example, the surface layers contain a proportion of chalk, with the proportion of chalk being between 15 and 40 wt.%.

[0042] In one variant of the invention, the chalk consists of CaCOs and has, for example, an organic coating.

[0043] For example, chalk has a mean particle size of more than 0.5 pm and less than 3 pm.

[0044] In one variant of the invention, the chalk has a mean particle size of more than 1.0 pm and less than 2 pm.

[0045] For example, chalk has a density of more than 2.0 g / cm³.3 and less than 3.2 g / cm³ 3 on.

[0046] Furthermore, it is planned that the cover layers will each have a small thickness of, for example, 1.5 pm and 6 pm, in particular 2 pm and 4 pm.

[0047] Ideally, the film, especially the top layers, is extremely elastic and soft due to the special selection and design composition, so that the film does not require an activation process and therefore does not suffer irreversible damage to the top layers.

[0048] Due to the special design of the cover layers with these polymers and these properties, the elastic film does not jam during winding and unwinding. Furthermore, the elastic film exhibits sufficiently high MD strength and slight CD stretchability even without activation.

[0049] However, the elastic film is not only soft and elastic due to the special design of the outer layers, but also due to the composition of the core layer. This core layer contains a first styrene block copolymer of more than 35 wt% and a second styrene block copolymer of less than 35 wt%.

[0050] For example, the proportion of the first styrene block copolymer in the core layer is more than 40 wt.% and less than 70 wt.%.

[0051] In one variant of the invention, the proportion of the first styrene block copolymer in the core layer is more than 43 wt.% and less than 53 wt.%.

[0052] For example, the proportion of the second styrene block copolymer in the core layer is more than 10 wt.% and less than 32.5 wt.%.

[0053] In one variant of the invention, the proportion of the second styrene block copolymer in the core layer is more than 20 wt.% and less than 30 wt.%.

[0054] The first styrene block copolymer exhibits an MFI (at 200 °C and at 5 kg) of more than 8 g / 10 min and less than 12 g / 10 min, which advantageously promotes blown extrusion and the shaping of elasticity.

[0055] For example, the first styrene block copolymer has a density of more than 0.94 g / cm³. 3 and of less than 0.96 g / cm³ 3 on.

[0056] The second styrene block copolymer exhibits a minimum flow rate (MFI) (at 200 °C and 5 kg) of more than 10 g / 10 min and less than 15 g / 10 min. For example, the second styrene block copolymer has a density of more than 0.92 g / cm³. 3 and of less than 0.94 g / cm³ 3 on.

[0057] In one variant of the invention, the first styrene block copolymer has a hardness of more than 58 Shore A and the second styrene block copolymer has a hardness of less than 58 Shore A.

[0058] For example, the first styrene block copolymer is designed as a styrene-isoprene-styrene block copolymer, wherein the styrene-isoprene-styrene block copolymer has a styrene content of more than 30 wt.% and less than 40 wt.%.

[0059] Styrene-isoprene-styrene (SIS) block copolymers are a specific class of thermoplastic elastomers composed of repeating units of styrene and isoprene in a block-like structure. They belong to the styrene block copolymer (SBC) family. The structure of an SIS block copolymer consists of hard styrene blocks surrounded by soft isoprene blocks. The hard styrene blocks impart strength, stiffness, and dimensional stability to the polymer, while the soft isoprene blocks provide elasticity, flexibility, and toughness.

[0060] In one variant of the invention, the second styrene block copolymer is designed as a styrene-isoprene-styrene block copolymer, wherein the styrene-isoprene-styrene block copolymer has a styrene content of more than 16 wt.% and less than 20 wt.%.

[0061] For example, the ratio of the proportion of the first styrene block copolymer to the proportion of the second styrene block copolymer in the core layer is between 2.8:1 and 1.3:1, preferably between 2.75:1 and 1.35:1, and particularly between 2.7:1 and 1.4:1. Furthermore, the core layer may also contain, for example, a proportion of polystyrene, wherein the proportion of polystyrene is between 3 wt.% and 15 wt.%.

[0062] For example, polystyrene has a density of more than 0.95 g / cm³. 3 and of less than 1.1 g / cm³ 3 on.

[0063] For example, polystyrene has an MFI at 200 °C and at 5 kg according to ISO 1133 of more than 8 g / 10 min and of less than 16 g / 10 min.

[0064] In one variant of the invention, the core layer contains a proportion of PE-POP, wherein the proportion of PE-POP is between 5 and 20 wt.%.

[0065] Polyolefin plastomers (POPs) are copolymers of ethylene and octene. Polyolefin plastomers bridge the gap between conventional elastomers and thermoplastics, contributing to a particularly elastic core layer.

[0066] For example, the PE-POP core layer exhibits an MFI (at 190 °C and at 2.16 kg) according to ASTM D1238 of more than 0.5 g / 10 min and less than 5.0 g / 10 min.

[0067] In one variant of the invention, the PE-POP of the core layer has a density of more than 0.86 g / cm³. 3 and of less than 0.89 g / cm³ 3 on.

[0068] The thickness of the core layer was determined according to DIN 53370 and is given as an average value. In one embodiment of the invention, the core layer has a thickness of more than 15 pm, preferably more than 25 pm, particularly more than 35 pm and / or less than 60 pm, preferably less than 50 pm, particularly less than 45 pm. This results in a particularly thin core layer, requiring minimal material while simultaneously exhibiting excellent elasticity without activation.

[0069] The thickness of the elastic film was determined according to DIN 53370 and is given as an average value. For example, the elastic film has a thickness of more than 20 pm, preferably more than 30 pm, particularly more than 40 pm and / or less than 70 pm, preferably less than 60 pm, particularly less than 50 pm.

[0070] For example, the at least one core layer and the at least two cover layers each have a thickness where the ratio of the core layer thickness to the cover layer thickness is more than 8 and less than 15, preferably more than 8.5 and less than 13.5, and particularly more than 9 and less than 12. This ratio reflects a particularly balanced ratio between the required tensile forces and the material savings achieved through the use of particularly thin films.

[0071] An elastic film in this particularly soft and elastic design without activation, while possessing good mechanical properties with regard to elongation and restoring force, is achieved through the special selection and realization of the correct proportion of PE-POP in both the cover layers and the core layer.

[0072] According to the invention, the elastic film is formed by a process for production by blown extrusion of at least one core layer with at least two cover layers.

[0073] In this process, the core layer and the two cover layers are in full contact after co-extrusion. The resulting elastic film with two non-elastic cover layers can then be rolled up, transported, and unrolled again without clogging due to the stickiness of the elastic film layer based on styrene block copolymers when rolled up.

[0074] In subsequent processing, the elastic film can, for example, be rolled on and off without excessive stretching because the cover layers are not irreversibly damaged in their structure by activation.

[0075] In one embodiment of the invention, the elastic film is bonded to at least one layer of nonwoven material in a form-fitting and / or material-bonded manner to form a laminate. A particular method for manufacturing the laminate from the elastic film and at least one corrugated layer of nonwoven material allows for the creation of areas with varying reserve capacities for a disposable hygiene product.

[0076] The connection areas between the elastic film and at least one corrugated nonwoven layer can be created using various methods. In one embodiment of the invention, a pre-solidified elastic film is unwound from a film roll, and a nonwoven layer with defined corrugations is fed into it. The elastic film and the nonwoven layer are joined together by connection areas, which are created by ultrasonic welding. In this process, the corrugated nonwoven material is subjected to external thermal stress.

[0077] In another variant, the bonding areas are created by pressing parts of the nonwoven layer into the molten elastic film. Alternatively, instead of molten extrusion, a pre-solid elastic film can be unwound from a roll and heated using heating rollers to create a bond with the nonwoven.

[0078] In one embodiment of the invention, the nonwoven layer consists of polypropylene. The terms "nonwoven" and "nonwoven" refer to polypropylene, which can be produced from continuous filaments and / or discontinuous fibers without weaving or knitting by processes such as spunbonding, carding, or meltblowing. The nonwoven fabric can comprise one or more layers, each layer potentially containing continuous filaments or discontinuous fibers.

[0079] In one option of the invention, the laminate has a further layer of nonwoven material, so that the elastic film is covered on both sides by a layer of nonwoven material.

[0080] For example, the elastic film is positioned between the two layers of nonwoven fabric. Due to the corrugated design, at least one layer of nonwoven fabric is significantly longer than the elastic film. A second layer of nonwoven fabric improves the feel of the disposable hygiene product for the wearer.

[0081] The second nonwoven layer can consist of either a hydroentangled nonwoven, a carded nonwoven, or a spunbond nonwoven. This second nonwoven layer can also be either corrugated or have a flat profile.

[0082] In one embodiment of the invention, the laminate of elastic film and nonwoven material comprises a layer of nonwoven material made from a carded nonwoven fabric. The carded nonwoven fabric used preferably consists of polypropylene fibers and / or mixtures of different fiber types, such as polypropylene / viscose, polypropylene / polyamide, polypropylene / polyester, etc. The carded nonwoven fabric can also consist of polypropylene and / or polyethylene copolymer. Preferably, the specific basis weight of the carded nonwoven fabric is 10 to 40 g / m². 2 , especially between 15 and 25 g / m² 2 The carded nonwoven fabric can be solidified, for example, by means of a calender and / or by exposure to air and / or a water jet.

[0083] Optionally, the laminate includes a nonwoven layer made from a spunbond nonwoven fabric. Spunbond nonwovens are known to be produced at very low basis weights. The spunbond nonwoven used preferably consists of polypropylene fibers and is thermally bonded. Alternatively and / or additionally, the nonwoven layer can also comprise meltblown nonwovens. Ideally, this nonwoven layer has a specific basis weight of more than 4 g / m². 2 , preferably more than 5 g / m² 2 , especially more than 6 g / m² 2 and / or less than 50 g / m² 2 , preferably less than 40 g / m² 2 , especially less than 30 g / m² 2 on.

[0084] According to the invention, a non-activated film is used as diaper ears for disposable hygiene products.

[0085] Further advantages and features of the invention will become apparent from the description of an exemplary embodiment with reference to two drawings and from the drawings themselves.

[0086] This shows

[0087] Fig. 1 shows a schematic structure of the elastic film according to the invention,

[0088] Fig. 2 shows the force-strain behavior in a hysteresis test of the elastic film. In Fig. 1, the elastic film 1 is shown with a core layer 3 based on styrene block copolymers, wherein the core layer 3 is arranged between soft cover layers 2 in a multilayer structure formed by coextrusion.

[0089] The thickness of the elastic film 1 was determined according to DIN 53370 and is 48 pm in the illustrated embodiment. The thickness of the soft cover layers 2 is 3 pm each, with the core layer 3 having a thickness of 42 pm.

[0090] The ratio of the thickness of the core layer 3 to the thickness of the cover layer 2 is 13.3.

[0091] In a hysteresis test in CD, a 25 mm (MD) and 100 mm (CD) section of elastic film 1 was cut. This prepared section was stretched in CD with a chuck spacing of 25 mm and a test speed of 254 mm / min to a chuck spacing of 80 mm (160%) and then released back to a chuck spacing of 25 mm. The force-strain behavior of the measured section of elastic film is shown in Fig. 2.

[0092] The elastic film 1 exhibits a force in CD of 3.2 N at a test speed of 254 mm / min and an elongation of 160 % at first load 4.

[0093] Furthermore, the elastic film 1 exhibits an elasticity in CD of 0.65 N at a test speed of 254 mm / min and an elongation of 8 % at second load 5.

[0094] The ratio of the force under first load 4 of the film 1 at an elongation of 160% to the force under second load 5 at an elongation of 8% is 5.0. The elastic film 1 with this particularly soft and elastic design of the cover layers 2 without additional activation is achieved by the selection and matching of the polymeric raw materials in the form of blown film. The invention of the elastic film 1 is explained below using an exemplary embodiment, without limiting the invention thereto.

[0095] Example 1

[0096] The surface layers are formed from the following raw materials:

[0097] The core layer is formed from the following substances:

Claims

Patent claims 1. Elastic film (1) with at least one core layer (3) based on styrene block copolymers, wherein the at least one core layer (3) is arranged between at least two cover layers (2), characterized in that the cover layers (2) have elastic properties without activation, wherein in a first load cycle the film (1) exhibits a force of less than 3.75 N at an elongation of 160%, wherein a film strip for the load cycle has a width of 25 mm in the MD direction and the film strip is fixed at a CD distance of 25 mm between grippers of a test device and the film strip is stretched in CD at a speed of 254 mm / min.

2. Film according to claim 1, characterized in that during the first load cycle the film (1) has a force of more than 2.75 N at an elongation of 160%, wherein a film strip for the load cycle has a width of 25 mm in the MD direction and the film strip is attached at a CD distance of 25 mm between grippers of a test device and the film strip is stretched in CD at a speed of 254 mm / min.

3. Film according to claim 1 or 2, characterized in that during the second load cycle the film (1) has a force of more than 0.4 N at an elongation of 8%, wherein a film strip for the load cycle has a width of 25 mm in the MD direction and the film strip is attached at a CD distance of 25 mm between grippers of a test device and the film strip is stretched in CD at a speed of 254 mm / min.

4. Film according to one of claims 1 to 3, characterized in that during the second load cycle the film (1) has a force of less than 1.0 N at an elongation of 8%, wherein a film strip for the load cycle has a width of 25 mm in the MD direction and the film strip is attached at a CD distance of 25 mm between grippers of a test device and the film strip is stretched in CD at a speed of 254 mm / min.

5. Film according to one of claims 1 to 4, characterized in that the ratio of the force during the first loading cycle of the film (1 ) at an elongation of 160 % to the force during the second loading cycle at an elongation of 8 % is greater than 5 and less than 8.

6. Film according to one of claims 1 to 5, characterized in that the cover layers (2) comprise a first polyethylene component and a second polyethylene component.

7. Film according to claim 6, characterized in that the first polyethylene component is made of a PE-POP, wherein the proportion of PE-POP is between 10 and 25 wt.%.

8. Film according to claim 6 or 7, characterized in that the first polyethylene component has an MFI (at 190 °C and at 2.16 kg) according to ASTM D1238 of more than 0.5 g / 10 min and of less than 5.5 g / 10 min.

9. Film according to one of claims 6 to 8, characterized in that the first polyethylene component has a density of more than 0.86 g / cm³ 3 and of less than 0.89 g / cm³ 3 exhibits.

10. Film according to one of claims 6 to 9, characterized in that the second polyethylene component is made of LLDPE, wherein the proportion of LLDPE is between 30 and 70 wt.%.

11. Film according to one of claims 6 to 10, characterized in that the second polyethylene component has an MFI (at 190 °C and at 2.16 kg) according to ASTM D1238 of more than 1.0 g / 10 min and of less than 4.0 g / 10 min.

12. Film according to one of claims 6 to 11, characterized in that the second polyethylene component has a density of more than 0.91 g / cm³ 3 and of less than 0.95 g / cm³ 3 exhibits.

13. Foil according to one of claims 1 to 12, characterized in that the cover layers (2) contain a proportion of chalk, wherein the proportion of chalk is between 15 and 40 wt.%.

14. Film according to one of claims 1 to 13, characterized in that the core layer (3) comprises a first styrene block copolymer of more than 35 wt.% and a second styrene block copolymer of less than 35 wt.%.

15. Film according to claim 14, characterized in that the first styrene- Block copolymer has a hardness of more than 58 Shore A and the second styrol- Block copolymer has a hardness of less than 58 Shore A.

16. Foil according to claim 14 or 15, characterized in that the first styrene block copolymer is designed as a styrene-isoprene-styrene block copolymer, wherein the styrene-isoprene-styrene block copolymer has a styrene content of more than 30 wt.% and less than 40 wt.%.

17. Film according to one of claims 14 to 16, characterized in that the second styrene block copolymer is designed as a styrene-isoprene-styrene block copolymer, wherein the styrene-isoprene-styrene block copolymer has a styrene content of more than 16 wt.% and less than 20 wt.%.

18. Film according to one of claims 14 to 17, characterized in that the ratio of the proportion of the first styrene block copolymer to the proportion of the second styrene block copolymer is between 2.8:1 and 1.3:

1.

19. Foil according to one of claims 1 to 18, characterized in that the core layer (3) has a proportion of polystyrene, wherein the proportion of polystyrene is between 3 wt.% and 15 wt.%.

20. Film according to one of claims 1 to 19, characterized in that the core layer (3) comprises a proportion of PE-POP, wherein the proportion of PE-POP content is between 5 and 20 wt.%.

21. Film according to one of claims 1 to 20, characterized in that the core layer (3) and the cover layers (2) each have a thickness, wherein the ratio of the thickness of the core layer (3) to the thickness of the cover layer (2) is more than 8 and less than 15.

22. Method for producing elastic film (1) according to one of the claims 1 to 16 with at least the following steps: - Bubble extrusion of at least one core layer (3) with at least two cover layers (2).

23. Use of a non-activated film (1) as diaper ears of disposable hygiene products

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