Deeply stretchable barrier membrane for fiber composite plastic parts

Abstract

The invention relates to a multilayer separator film comprising a first surface layer based on a mixture of a thermoplastic elastomer and a polyolefin, a second surface layer based on at least one polypropylene or propylene copolymer, and an adhesion promoting layer, the separator film having a total layer thickness in the range of 10 to 250 [mu] m. The separator according to the invention is suitable for the production of fiber composite plastic parts, in particular by a vacuum infusion process.

Description

[0001] describe

[0002] Priority is claimed from German patent application No. 10 2022 105 691.0 filed on March 10, 2022.

[0003] The invention relates to a multilayer barrier film comprising a first surface layer based on a mixture of a thermoplastic elastomer and a polyolefin, a second surface layer based on at least one polypropylene or a propylene copolymer, and an adhesion-promoting layer, wherein the barrier film has a total layer thickness in the range of 10 to 250 μm. The barrier film according to the invention is suitable for producing fiber composite plastic parts, in particular by vacuum infusion processes.

[0004] With the aid of release films or vacuum bags made therefrom, even fiber composite plastic parts of complex design can be produced for a wide variety of applications, such as for the aviation, aerospace, automotive or wind energy industries. A curable fiber composite plastic semi-finished product, for example a laminate made of carbon fibers or glass fibers, impregnated with a plastic resin to be cured, is placed in a vacuum bag. In principle, the vacuum bag can be formed by a single release film which completely surrounds the curable fiber composite plastic semi-finished product. In practice, however, the vacuum bag usually consists of several elements joined together in a vacuum-tight manner.

[0005] In some technologies, the semi-finished product is already pre-impregnated with plastic resin (e.g. pre-impregnated fibers (prepreg), pre-impregnated metal grids, etc.), while other technologies are based on non-pre-impregnated semi-finished products, which are then impregnated with plastic resin in a vacuum bag (e.g. in the infusion process).

[0006] The curable semi-finished product is then pressed into a shaped vacuum-tight tool by evacuation and compacted therein sufficiently so that gas or air inclusions can escape and the laminate has as few cavities as possible. The evacuable overall arrangement consisting of the vacuum bag, the forming tool and the formed curable fiber composite plastic semi-finished product is then heated in an autoclave at high pressure and temperature until the plastic resin is heated to the curing temperature of the plastic resin. After cooling, the cured fiber composite plastic part can be removed from the vacuum bag and separated from the vacuum-tight forming tool.

[0007] Fiber composite plastic parts are often manufactured in molds using insulation to prevent the used curable plastic resin from adhering to the mold. The use of such insulation is time-consuming and costly, especially when producing large-area fiber composite plastic parts such as wind turbine blades.

[0008] In most cases, the production of wind turbine blades is carried out using a vacuum infusion process in moulds, each of which forms one half of the blade. The moulds are coated with a liquid release agent in order to achieve a release effect between the cured plastic resin of the fibre composite plastic part and the mould after the curable plastic resin introduced in liquid form (usually an epoxy resin or, in a few cases, a polyester resin system) has cured.

[0009] The use of these release agents has numerous disadvantages. For example, there is a risk of damage to the mold due to insufficient coverage with the release agent. In addition, the surface of the fiber-composite plastic part must be carefully reworked before paint and varnish can be applied in order to achieve an adequate surface quality. In particular, any unevenness must be sealed with fillers (so-called pore fillers) and the correspondingly machined surface of the fiber-composite plastic part must then be sanded. This surface treatment is very time-consuming and costly. The fine dust generated and the release agents used in this way also pose a health risk to the operating personnel.

[0010] WO 2014124945A 1 relates to a siliconized insulating film for producing molded plastic parts from fiber composite materials using a mold, comprising a carrier film that can be deep-drawn in vacuum at room temperature and a coating that can be applied in liquid form, the coating optionally consisting of more than 90 atomic % of silicon, carbon and / or oxygen, more than 45 atomic % of carbon and more than 20 atomic % of silicon after removal of any solvent, in each case based on the entire coating and measured by XPS, characterized in that the coating is crosslinked by an addition reaction, a condensation reaction or by radiation.

[0011] US20170066218A1 and US20190322075A1 relate to a multilayer release film having a first outer layer comprising polymethylpentene or a fluorinated polymer and having a first adhesive affinity, and a second outer layer comprising polymethylpentene or a fluorinated polymer and an adhesive regulating additive. The second outer layer has a second adhesive affinity different from the first adhesive affinity of the first outer layer. The difference in adhesive affinity between the first and second outer layers of the release film enables the film to have the performance of being completely separated from the mold.

[0012] EP 0 364956 discloses a laminate comprising (A) a 4-methyl-1-pentene polymer layer, (B) a polymer composition layer comprising (a) 40 wt % to 49 wt % of a random ethylene / a-olefin copolymer containing 30 mol % to 95 mol % of ethylene units, (b) 0.1 wt % to 20 wt % of a polyolefin modified with an unsaturated carboxylic acid or a derivative thereof, and (d) 1 wt % to 50 wt % of a tackifier, the proportions of components (a), (b) and (d) being based on the total weight of components (a), (b) and (d), and (d) a thermoplastic resin layer, wherein layers (A), (B) and (d) are laminated in the order shown.

[0013] EP 0 376681 discloses a barrier film consisting of a laminate comprising: (a) an intermediate layer comprising at least one flexible polyolefin layer, and (b) two crystalline polymethylpentene outer layers, one on each side of the intermediate layer.

[0014] US 5,123,985 relates to vacuum bags made of thermoplastic elastomer films that readily conform to the surface contours of a workpiece without interruption at low pressures. Thermoplastic elastomer films can be processed into thin films that can withstand high pressures and temperatures.

[0015] WO 00 / 59720 discloses a multilayer barrier film containing polymethylpentene, a method for its preparation and its use in the manufacture of articles containing cured fiber composite epoxy resins, phenolic resins or polyacrylate compositions, which can be used as structural elements for aerospace applications. When exposed to high temperatures, the film has improved separation properties. The film is non-oriented and multilayer and comprises a polyamide layer, a polymethylpentene layer and an intermediate adhesive layer. The barrier film has a total layer thickness of preferably 15 to 30 μm and is therefore dimensionally unstable and cannot be deep-stretched.

[0016] US 2012 / 0175043 discloses a method for applying multiple polymer coatings to a fibrous substrate, in particular a method for applying multiple polymer coatings to a fibrous substrate without having to consider chemical or physical incompatibility of the polymer coating materials.

[0017] WO 2013 / 160437 discloses a composite material comprising (i) a plastic molded part or (ii) a plastic semi-finished product with a protective coating system, wherein the protective coating system comprises a plastic film and a plasma polymer silicone layer. WO 2013 / 160437 also relates to the use of a temporary protective film as a release aid between a mold or a mold and the resulting plastic molded part in a plastic molding process, and a method for producing a composite material comprising a plastic molded part and a temporary protective film.

[0018] US2015 / 0266276 discloses a composite material comprising (i) a plastic component or (ii) a plastic semi-finished product having a protective coating system, wherein the protective coating system comprises a plastic film and an organosilicon plasma polymer layer, wherein the organosilicon plasma polymer layer is arranged between (i) the plastic component or (ii) the plastic semi-finished product and the plastic film; and wherein after the (i) plastic component or (ii) the plastic semi-finished product is cured, the adhesion of the organosilicon plasma polymer layer to the plastic film is better than the adhesion to the (i) plastic component or (ii) the plastic semi-finished product.

[0019] WO 2017 / 068152 discloses a composite component (10) characterized by the following layer structure: a) a layer (11) which is at least partially composed of polyethylene, b) a layer (12) which is at least partially composed of polyurethane and / or an elastomer, c) at least one layer (13) which is at least partially composed of a plastic reinforced by fibers (14) or which is at least partially composed of an adhesive, the layer (12) being arranged directly between the layer (11) and the layer (13), the layers (11) and (12) having been joined in a first operation to form a laminated composite material, and the layer (13) having been joined to the laminated composite material comprising the layers (11) and (12) in a second operation.

[0020] DE 102007010071A1 relates to a laminate comprising a lacquer layer and a barrier layer and a lacquer carrier arrangement for transferring lacquer. The laminate comprises a lacquer layer and a barrier layer, wherein (a) the lacquer layer consists of uncured and / or partially cured and / or cured lacquer, and (b) the barrier layer is a plasma polymer layer consisting of carbon, silicon, oxygen and hydrogen and optionally conventional impurities.

[0021] There is a need for a release film which is suitable for the production of fiber composite plastic parts, in particular by vacuum infusion processes, and which has advantages over the prior art. The release film should make it unnecessary to use liquid release agents in the production of the fiber composite plastic parts. Furthermore, the release film should be made from a carrier film obtainable by blown film coextrusion and provide an inherent release effect. The release film should also be deep-stretchable and able to withstand the temperatures generated during the exothermic curing of the plastic resin. Furthermore, the release film should be able to remain on the surface of the cured fiber composite plastic part for a certain period of time to act as a protective film, but should be able to be removed therefrom without difficulty at a given time in order to expose the surface of the fiber composite plastic part. Furthermore, the release film should have sufficient separation properties on the side facing away from the fiber composite plastic part, i.e. the outer side, compared to the so-called "sticky tape" which is usually used to bond the web of the release film together or to fix (bag) the film to the tool mold.

[0022] This object is achieved by the subject matter of the claims.

[0023] Surprisingly, it has been found that it is possible to provide a deep-stretchable release film which, after thermoforming, replicates the mold of the fiber-composite plastic component one-to-one like a protective skin, making it no longer possible to damage the mold surface.

[0024] Furthermore, it has surprisingly been found that due to the relatively high stretchability, it is possible to produce a release film which supports deep drawing of the release film at low forces. The use of the release film according to the invention leads to a very flat surface of the cured fiber-composite plastic component. The need for reworking the surface is therefore greatly reduced and, in the ideal case, even avoided completely. Process cost advantages can be achieved by saving material (release agent, filler) and working time for applying the filler and grinding the surface. At the same time, there are also advantages in terms of employee health protection, since there is no need to handle release agents and employees are no longer exposed to fine dust when grinding the surface of the cured fiber-composite plastic component.

[0025] Furthermore, it has surprisingly been found that deep-stretchable release films can be provided which do not require a release coating based on organosilicon compounds and which have intrinsic release properties with respect to the plastic resin used, whereby the release properties are achieved solely by the composition of the release film.

[0026] A further advantage of the barrier film according to the invention is that it can remain on the surface of the cured fiber-composite plastic component for a relatively long period of time, depending on the climate zone, for 3 to 6 months, even outdoors, thereby protecting the surface from environmental influences during storage.

[0027] Furthermore, it was surprisingly found that the first surface layer facing the mold, which is based on a thermoplastic polyester elastomer, has sufficient release properties to the mold. This enables the release membrane according to the invention to be repositioned when inserted into the mold. The low force absorption and plastic deformation (which already begins at low elongations) of the release membrane according to the invention have the additional advantage that the release membrane does not exert any horizontal tensile forces on the "sticky tape" in the deeply stretched state; thus avoiding leakage.

[0028] Furthermore, it has surprisingly been found that the time required for reprocessing of fiber composite plastic components can be significantly reduced by using the release film according to the invention. This reduces the costs usually incurred for reprocessing of fiber composite plastic components (e.g. due to the maintenance costs of the space required for processing (such as a hall or hall area), the equipment for processing the surface (such as grinding equipment), and the disposal costs of grinding waste (such as dust and sandpaper)).

[0029] A first aspect of the present invention relates to a multi-layer isolation film comprising

[0030] - a first surface layer based on a mixture of a thermoplastic elastomer and a polyolefin;

[0031] - an adhesion promoting layer;

[0032] - an optional first intermediate layer;

[0033] - an optional second intermediate layer; and

[0034] - a second surface layer based on at least one polypropylene or a propylene copolymer;

[0035] The isolation film has a total layer thickness in the range from 10 to 250 μm.

[0036] The first surface layer and the second surface layer are located on both sides of the two outer surfaces of the isolation film according to the present invention. Therefore, the first surface layer and the second surface layer are each in direct contact with another layer of the isolation film according to the present invention only on one of their two sides; the corresponding back-to-back layer forms the outer surface of the isolation film according to the present invention.

[0037] When a fiber composite plastic part is produced in a mold using the release film according to the invention, the first surface layer is intended to face the mold, while the second surface layer is in contact with the curable plastic resin and is detachably attached thereto. In the composite of release film and fiber composite plastic part, the first surface layer of the release film forms the outside of the composite material, while the second surface layer of the release film forms the inside of the composite material.

[0038] The first intermediate layer and the second intermediate layer are each, independently of each other, optional.

[0039] In a preferred embodiment

[0040] (i) The release film according to the present invention is composed of a first surface layer, an adhesion promoting layer and a second surface layer;

[0041] (ii) the release film according to the present invention comprises or consists of a first surface layer, an adhesion promoting layer, a first intermediate layer and a second surface layer; or

[0042] (iii) the release film according to the present invention comprises or consists of a first surface layer, an adhesion promoting layer, a first intermediate layer, a second intermediate layer, and a second surface layer;

[0043] Preferably, the above-mentioned layer sequence is followed in each case.

[0044] In principle, in addition to the aforementioned layers, any additional layers may also be present. Thus, the separator according to the invention has at least three layers, but in principle may also have four, five, six, seven or more layers, wherein a five-layer structure is preferred.

[0045] Unless expressly stated otherwise, percentages are by weight. Unless expressly stated otherwise, the versions of standards such as ENISO, ASTM, FINAT, etc. effective January 1, 2021 shall apply.

[0046] Unless otherwise expressly stated, the term "based on" means that the component is the main component by weight, which may be a mixture of several components. The main component does not necessarily account for more than 50% by weight; it only must not have other components with a larger weight proportion.

[0047] The first surface layer of the release film according to the invention is based on a mixture of a thermoplastic elastomer and a polyolefin.

[0048] Surprisingly, it is found that the mixture of thermoplastic elastomer and polyolefin according to the present invention has special advantages, especially when they are incompatible with each other. For example, when the thermoplastic elastomer is a thermoplastic polyester elastomer and the polyolefin is polyethylene (particularly LLDPE), this is the case. Polyethylene then acts as an anti-blocking agent in the thermoplastic polyester elastomer, thereby producing a surface roughness that is conducive to blown film coextrusion, which may not be possible or difficult to achieve using conventional anti-blocking agents (such as talcum masterbatch). This prevents wrinkling and sticking to the roller during extrusion, for example, thereby resulting in an improvement in blown film coextrusion.

[0049] Furthermore, it was surprisingly found that the first surface layer has a sufficient release effect compared to "sticky tapes" coated with butyl adhesive for sealing the mould.

[0050] Thermoplastic elastomers are known to those skilled in the art and are commercially available. At room temperature, they behave like conventional, ie non-thermoplastic, elastomers, but can deform plastically upon application of heat, thereby exhibiting thermoplastic behavior. Preferred thermoplastic elastomers according to the invention are selected from the group consisting of thermoplastic polyamide elastomers; thermoplastic polyester elastomers (copolyester elastomers); olefin-based thermoplastic elastomers, such as polypropylene / ethylene-propylene-diene rubber (PP / EPDM); thermoplastic styrene block copolymers (styrene-butadiene-styrene block copolymers (SBS), styrene-ethylene-butylene-styrene block copolymers (SEBS), styrene-ethylene-propylene-styrene block copolymers (SEPS), styrene-ethylene-ethylene-propylene-styrene block copolymers (SEEPS) and methyl acrylate-butadiene-styrene copolymers (MBS), styrene-isoprene-styrene block copolymers (SIS), styrene-isoprene-butylene copolymers (SIBS)); polyurethane-based thermoplastic elastomers; and thermoplastic vulcanizates or crosslinked olefin-based thermoplastic elastomers, such as PP / EPDM. For example PP / EPDM.

[0051] Preferably, the thermoplastic elastomer is a thermoplastic polyester elastomer. Thermoplastic polyester elastomers are known to the person skilled in the art and are commercially available, for example under the trade name (Du Pont), (LG Chem) and (SK Chemicals).

[0052] In a particularly preferred embodiment, the thermoplastic elastomer in the first surface layer has a DSC melting temperature according to ISO 11357-3 of

[0053] - at least 150°C; preferably at least 155°C, more preferably at least 160°C, still more preferably at least 165°C; and / or

[0054] - at most 190°C; preferably at most 185°C, more preferably at most 180°C, still more preferably at most 175°C; and / or

[0055] - In the range of 170±24°C; preferably 170±16°C, more preferably 170±8°C.

[0056] Thermoplastic elastomers, in particular thermoplastic polyester elastomers having such properties, are known to the person skilled in the art and are commercially available, for example as G4078NC010.

[0057] Polyolefins are known to those skilled in the art and are commercially available. Preferably, the polyolefin is selected from the group consisting of polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), polyisobutylene (PIB), polybutene (PB, polybutene-1), copolymers thereof and / or mixtures thereof.

[0058] Preferred polyethylenes include low-density polyethylene (LDPE / PE-LD), linear low-density polyethylene (LLDPE / PE-LLD), and high-density polyethylene (HDPE / PE-HD), with LLDPE being particularly preferred.

[0059] Preferred polypropylenes include atactic polypropylene, isotactic polypropylene, syndiotactic polypropylene and heterophasic polypropylene. Heterophasic polypropylene is typically a copolymer of ethylene and propylene, typically polymerized using a Ziegler-Natta catalyst.

[0060] Preferably, the polyolefin in the first surface layer is polyethylene or an ethylene copolymer; preferably LLDPE.

[0061] In a particularly preferred embodiment, the polyolefin in the first surface layer has a melt flow index MFI 190° C., 2.16 kg / m² according to ISO 1133 of

[0062] - at least 0.7 g / 10 min; preferably at least 0.8 g / 10 min, more preferably at least 0.9 g / 10 min, even more preferably at least 1.0 g / 10 min; and / or

[0063] - at most 1.5 g / 10 min; preferably at most 1.4 g / 10 min, more preferably at most 1.3 g / 10 min, still more preferably at most 1.2 g / 10 min; and / or

[0064] - In the range of 1.1±0.3 g / 10 min; preferably 1.1±0.2 g / 10 min, more preferably 1.1±0.1 g / 10 min.

[0065] In a particularly preferred embodiment, the polyolefin in the first surface layer has a Vicat softening temperature according to ASTM D1525 of

[0066] - at least 96°C; preferably at least 98°C, more preferably at least 100°C, even more preferably at least 102°C; and / or

[0067] - at most 112°C; preferably at most 110°C, more preferably at most 108°C, still more preferably at most 106°C; and / or

[0068] - In the range of 104±9°C; preferably 104±6°C; more preferably 104±3°C.

[0069] In a particularly preferred embodiment, the polyolefin in the first surface layer has a density according to ASTM D792 of

[0070] - At least 0.900g / cm 3 ; preferably at least 0.905g / cm 3 , more preferably at least 0.910 g / cm 3 , even more preferably at least 0.915 g / cm 3 ; and / or

[0071] - Up to 0.940 g / cm 3 ; preferably up to 0.935g / cm 3 , more preferably at most 0.930 g / cm 3 , even more preferably at most 0.925 g / cm 3 ; and / or

[0072] -0.919±0.020g / cm 3 In the range of; preferably 0.919 ± 0.015g / cm 3 , more preferably 0.919±0.010g / cm 3 , still more preferably 0.919±0.005 g / cm3 .

[0073] Polyolefins, in particular polyethylene or ethylene copolymers such as LLDPE, having such properties are known to the person skilled in the art and are commercially available, for example as NG 5056 G.

[0074] In a preferred embodiment, the weight proportion of the thermoplastic elastomer in the first surface layer is greater than the weight proportion of the polyolefin.

[0075] Preferably, the weight proportion of the thermoplastic elastomer in the first surface layer is in the range of 72±25 weight % based on the total weight of the first surface layer; preferably 72±20 weight %, more preferably 72±15 weight %, even more preferably 72±10 weight %, most preferably 72±5 weight %.

[0076] Preferably, the weight percentage of polyolefin in the first surface layer is in the range of 10±9 wt% based on the total weight of the first surface layer; preferably 10±8 wt%, more preferably 10±7 wt%, even more preferably 10±6 wt%, most preferably 10±5 wt%.

[0077] Layer thickness of the first surface layer

[0078] - preferably at least 5 μm; preferably at least 6 μm, more preferably at least 7 μm, even more preferably at least 8 μm; and / or

[0079] - preferably at most 13 μm; preferably at most 12 μm, more preferably at most 11 μm, even more preferably at most 10 μm; and / or

[0080] - preferably in the range of 9±7 μm; preferably 9±5 μm; more preferably 9±3 μm.

[0081] The second surface layer of the release film according to the present invention is based on at least one polypropylene or propylene copolymer.

[0082] Preferably, the at least one polypropylene or propylene copolymer in the second surface layer comprises at least one heterophasic polypropylene.

[0083] Preferably, the weight proportion of the at least one polypropylene or propylene copolymer in the second surface layer is in the range of 88±12 wt.-%, based on the total weight of the second surface layer; preferably 88±10 wt.-%, more preferably 88±8 wt.-%, even more preferably 88±6 wt.-%, most preferably 88±4 wt.-%.

[0084] In an especially preferred embodiment the at least one polypropylene or propylene copolymer in the second surface layer is a mixture of a first heterophasic polypropylene and a second heterophasic polypropylene different therefrom.

[0085] It was surprisingly found that the extrusion film bubble can be stable in blown film coextrusion when using a blend of two different heterophasic polypropylenes.

[0086] Preferably, the weight proportion of the first heterophasic polypropylene in the second surface layer is at most 60 wt-%, based on the total weight of the second surface layer; preferably at most 50 wt-%, more preferably at most 40 wt-%, even more preferably at most 30 wt-%.

[0087] Preferably, the weight proportion of the first heterophasic polypropylene in the second surface layer is in the range of 20±12 wt% based on the total weight of the second surface layer; preferably 20±10 wt%, more preferably 20±8 wt%, still more preferably 20±6 wt%, most preferably 20±4 wt%.

[0088] Preferably, the first heterophasic polypropylene has a lower melt flow rate and / or a lower DSC melting temperature than the second heterophasic polypropylene.

[0089] In a particularly preferred embodiment, the first heterophasic polypropylene has a melt flow rate MFR 230° C., 2.16 kg / m² according to ISO 1133-1 of

[0090] - at least 0.2 g / 10 min; preferably at least 0.3 g / 10 min, more preferably at least 0.4 g / 10 min, even more preferably at least 0.5 g / 10 min; and / or

[0091] - at most 1.0 g / 10 min; preferably at most 0.9 g / 10 min, more preferably at most 0.8 g / 10 min, even more preferably at most 0.7 g / 10 min; and / or

[0092] - in the range of 0.6±0.3 g / 10 min; preferably 0.6±0.2 g / 10 min, more preferably 0.6±0.1 g / 10 min;

[0093] In a particularly preferred embodiment the first heterophasic polypropylene has a DSC melting temperature according to ISO 11357-3 of

[0094] - at least 125°C; preferably at least 130°C, more preferably at least 135°C, still more preferably at least 140°C; and / or

[0095] - at most 165°C; preferably at most 155°C, more preferably at most 150°C, still more preferably at most 145°C; and / or

[0096] - In the range of 142±24°C; preferably 142±16°C, more preferably 142±8°C.

[0097] Heterophasic polypropylenes having such properties are known to the person skilled in the art and are commercially available, for example as Q 100F.

[0098] Preferably, the weight proportion of the second heterophasic polypropylene in the second surface layer is at least 30 wt-%, based on the total weight of the second surface layer; preferably at least 40 wt-%, more preferably at least 50 wt-%, even more preferably at least 60 wt-%.

[0099] Preferably, the weight proportion of the second heterophasic polypropylene in the second surface layer is in the range of 68±12 wt-%, based on the total weight of the second surface layer; preferably 68±10 wt-%, more preferably 68±8 wt-%, still more preferably 68±6 wt-%, most preferably 68±4 wt-%.

[0100] In a particularly preferred embodiment, the second heterophasic polypropylene has a melt flow rate MFR 230°C, 2.16 kg / m2 according to ISO 1133-1 of

[0101] - at least 0.5 g / 10 min; preferably at least 0.6 g / 10 min, more preferably at least 0.7 g / 10 min, even more preferably at least 0.8 g / 10 min; and / or

[0102] - at most 1.2 g / 10 min; preferably at most 1.1 g / 10 min, more preferably at most 1.0 g / 10 min, even more preferably at most 0.9 g / 10 min; and / or

[0103] - in the range of 0.85±0.3 g / 10 min; preferably 0.85±0.2 g / 10 min, more preferably 0.85±0.1 g / 10 min.

[0104] In a particularly preferred embodiment the second heterophasic polypropylene has a DSC melting temperature according to ISO 11357-3 of

[0105] - at least 150°C; preferably at least 155°C, more preferably at least 160°C, still more preferably at least 165°C; and / or

[0106] - at most 185°C; preferably at most 180°C, more preferably at most 175°C, still more preferably at most 170°C; and / or

[0107] - In the range of 166±24°C; preferably 166±16°C, more preferably 166±8°C.

[0108] Heterophasic polypropylenes having such properties are known to the person skilled in the art and are commercially available, for example as BA110CF.

[0109] Preferably, the layer thickness of the second surface layer is greater than the layer thickness of the first surface layer.

[0110] Layer thickness of the second surface layer

[0111] - preferably at least 6 μm; preferably at least 8 μm, more preferably at least 10 μm, even more preferably at least 12 μm; and / or

[0112] - preferably at most 22 μm; preferably at most 20 μm, more preferably at most 18 μm, still more preferably at most 16 μm; and / or

[0113] - preferably in the range of 14±12 μm; preferably 14±9 μm; more preferably 14±6 μm.

[0114] The release film according to the invention comprises an adhesion-promoting layer. For this purpose, the adhesion-promoting layer is usually based on a material that is compatible in each case with the materials on which the two layers directly adjacent to the adhesion-promoting layer are based. Suitable materials are known to those skilled in the art and are commercially available.

[0115] Preferably, the two layers immediately adjacent to the adhesion-promoting layer are the first surface layer and the first intermediate layer or the second surface layer.

[0116] Therefore, the adhesion promoting layer is preferably arranged between the first surface layer and the first intermediate layer. Preferably, the adhesion promoting layer is directly adjacent to the first surface layer. Preferably, the adhesion promoting layer is directly adjacent to the first intermediate layer (on the opposite side thereof).

[0117] Preferably, the adhesion promoting layer is based on ethylene-acrylate copolymers. Ethylene-acrylate copolymers suitable for producing such adhesion promoting layers are known to those skilled in the art and are commercially available.

[0118] Surprisingly it has been found that ethylene-acrylate copolymers exhibit a good adhesion promoting effect, whereas conventional adhesion promoters, for example adhesion promoters based on polyethylene, polypropylene or elastomers grafted with maleic anhydride, do not exhibit a sufficient adhesion promoting effect.

[0119] The adhesion-promoting layer is preferably non-reactive, i.e. it is different from conventional reactive adhesives and other conventional adhesion promoters. This ensures that the release film according to the invention can be thermoformed, in particular deep drawn, or cold formed. Preferably, the adhesion-promoting layer is essentially based only on thermoplastic polymers.

[0120] The release film according to the invention preferably has a high bond strength, so that the layers cannot be separated under the usual measurement conditions prescribed for determining the bond strength, ie delamination is prevented under stress conditions. This is ensured, among other things, by the adhesion-promoting layer.

[0121] In a particularly preferred embodiment, the ethylene-acrylate copolymer has a melt flow index MFI 190° C., 2.16 kg / m² according to ISO 1133 of

[0122] - at least 1.6 g / 10 min; preferably at least 1.7 g / 10 min, more preferably at least 1.8 g / 10 min, even more preferably at least 1.9 g / 10 min; and / or

[0123] - at most 2.4 g / 10 min; preferably at most 2.3 g / 10 min, more preferably at most 2.2 g / 10 min, even more preferably at most 2.1 g / 10 min; and / or

[0124] - in the range of 2.0±0.3 g / 10 min; preferably 2.0±0.2 g / 10 min, more preferably 2.0±0.1 g / 10 min;

[0125] In a particularly preferred embodiment, the ethylene-acrylate copolymer has a DSC melting temperature according to ISO 11357-3 of

[0126] - at least 75°C; preferably at least 80°C, more preferably at least 85°C, still more preferably at least 90°C; and / or

[0127] - at most 110°C; preferably at most 105°C, more preferably at most 100°C, still more preferably at most 95°C; and / or

[0128] - in the range of 91±12°C; preferably 91±8°C; more preferably 91±4°C;

[0129] In a particularly preferred embodiment, the ethylene-acrylate copolymer has a Vicat softening temperature according to ASTM D1525 of

[0130] - at least 40°C; preferably at least 42°C, more preferably at least 44°C, still more preferably at least 46°C; and / or

[0131] - at most 65°C; preferably at most 60°C, more preferably at most 55°C, still more preferably at most 50°C; and / or

[0132] - within the range of 48±12°C; preferably 48±8°C, more preferably 48±4°C.

[0133] Ethylene-acrylate copolymers having such properties are known to the person skilled in the art and are commercially available, for example as 22E 780.

[0134] Preferably, the weight proportion of the ethylene-acrylate copolymer in the adhesion promoting layer is at least 75 wt % based on the total weight of the adhesion promoting layer; more preferably at least 80 wt %, more preferably at least 85 wt %, even more preferably at least 90 wt %, most preferably at least 95 wt %.

[0135] Layer thickness of the adhesion promoting layer

[0136] - preferably at least 0.5 μm; preferably at least 1.0 μm, more preferably at least 1.5 μm, even more preferably at least 2.0 μm; and / or

[0137] - preferably at most 7 μm; preferably at most 6 μm, more preferably at most 5 μm, even more preferably at most 4 μm; and / or

[0138] - preferably in the range of 3±2 μm; preferably 3±1 μm.

[0139] The release film according to the present invention preferably has a first intermediate layer in addition to the first and second surface layers and the adhesion-promoting layer.

[0140] If the release film according to the invention also has a second intermediate layer, the first intermediate layer preferably has a greater layer thickness than the second intermediate layer.

[0141] Surprisingly, it has been found that the first intermediate layer, possibly in cooperation with the second intermediate layer, improves the properties of the release film according to the invention. Surprisingly, it has been found that a relatively soft deep-stretchable intermediate layer with a temperature resistance of >140° C. is advantageous, since during the exothermic curing of plastic resins (e.g. epoxy resins), temperature peaks of up to 135° C. can be reached.

[0142] In a preferred embodiment, the first intermediate layer is arranged between the adhesion promoting layer and the second intermediate layer. In a preferred embodiment, the first intermediate layer is directly adjacent to the adhesion promoting layer. In a preferred embodiment, the first intermediate layer is directly adjacent to the second intermediate layer (on opposite sides thereof).

[0143] Layer thickness of the first intermediate layer

[0144] - preferably at least 5 μm; preferably at least 6 μm, more preferably at least 7 μm, even more preferably at least 8 μm; and / or

[0145] - preferably at most 16 μm; preferably at most 14 μm, more preferably at most 121 μm, even more preferably at most 10 μm; and / or

[0146] - preferably in the range of 9±8 μm; preferably 9±6 μm; more preferably 9±4 μm.

[0147] Preferably, the first intermediate layer is based on at least one polypropylene or propylene copolymer, preferably on at least one heterophasic polypropylene.

[0148] In an especially preferred embodiment the first intermediate layer is based on a mixture of a third heterophasic polypropylene and a fourth heterophasic polypropylene.

[0149] In a preferred embodiment the third heterophasic polypropylene has a lower melt flow rate and / or a higher DSC melting temperature than the fourth heterophasic polypropylene in the first intermediate layer.

[0150] Preferably, the weight proportion of the third heterophasic polypropylene in the first intermediate layer is in the range of 0 to 83.5 wt.-%, based on the total weight of the first intermediate layer. Preferably, the weight proportion of the third heterophasic polypropylene in the first intermediate layer is in the range of 34±12 wt.-%, based on the total weight of the first intermediate layer; preferably 34±10 wt.-%, more preferably 34±8 wt.-%, even more preferably 34±6 wt.-%, most preferably 34±4 wt.-%.

[0151] In a more preferred embodiment, the weight proportion of the third heterophasic polypropylene in the first intermediate layer is in the range of 58±12 wt-%, based on the total weight of the first intermediate layer; preferably 58±10 wt-%, more preferably 58±8 wt-%, still more preferably 58±6 wt-%, most preferably 58±4 wt-%.

[0152] In a more preferred embodiment, the weight proportion of the third heterophasic polypropylene in the first intermediate layer is based on the total weight of the first intermediate layer.

[0153] - at least 35 wt. %, preferably at least 40 wt. %, more preferably at least 45 wt. %, even more preferably at least 50 wt. %, most preferably at least 55 wt. %; and / or

[0154] - at most 55 wt.-%, preferably at most 50 wt.-%, more preferably at most 45 wt.-%, even more preferably at most 40 wt.-%, most preferably at most 35 wt.-%.

[0155] Preferably, the weight proportion of the fourth heterophasic polypropylene in the first intermediate layer is in the range of 0 to 83.5 wt.-%, based on the total weight of the first intermediate layer. Preferably, the weight proportion of the fourth heterophasic polypropylene in the first intermediate layer is in the range of 48±12 wt.-%, based on the total weight of the first intermediate layer; preferably 48±10 wt.-%, more preferably 48±8 wt.-%, even more preferably 48±6 wt.-%, most preferably 48±4 wt.-%.

[0156] In a more preferred embodiment the weight proportion of the fourth heterophasic polypropylene in the first intermediate layer is in the range of 40±6 wt%; preferably 40±4 wt%, more preferably 40±2 wt%, based on the total weight of the first intermediate layer.

[0157] In a more preferred embodiment, the weight proportion of the fourth heterophasic polypropylene in the first intermediate layer is based on the total weight of the first intermediate layer.

[0158] - at least 40% by weight, preferably at least 45% by weight; and / or

[0159] - at most 50% by weight, preferably at most 45% by weight, more preferably at most 40% by weight.

[0160] The release film according to the present invention preferably has a second intermediate layer in addition to the first surface layer, the second surface layer, the adhesion-promoting layer and the first intermediate layer (if present).

[0161] In a preferred embodiment, the second intermediate layer is arranged between the first intermediate layer and the second surface layer. In a preferred embodiment, the second intermediate layer is directly adjacent to the first intermediate layer. In a preferred embodiment, the second intermediate layer is directly adjacent to (on the opposite side of) the second surface layer.

[0162] Layer thickness of the second intermediate layer

[0163] - preferably at least 1 μm; preferably at least 2 μm, more preferably at least 3 μm, even more preferably at least 4 μm; and / or

[0164] - preferably at most 9 μm; preferably at most 8 μm, more preferably at most 7 μm, even more preferably at most 6 μm; and / or

[0165] - preferably in the range of 5±4 μm; preferably 5±3 μm; more preferably 5±2 μm.

[0166] Preferably, the second intermediate layer is based on at least one polypropylene or propylene copolymer, preferably on at least one heterophasic polypropylene.

[0167] In an especially preferred embodiment the second intermediate layer is based on a mixture of a fifth heterophasic polypropylene and a sixth heterophasic polypropylene different therefrom.

[0168] In a preferred embodiment the fifth heterophasic polypropylene has a lower melt flow rate and / or a higher DSC melting temperature than the sixth heterophasic polypropylene in the second intermediate layer.

[0169] Preferably, the weight proportion of the fifth heterophasic polypropylene in the second intermediate layer is in the range of 0 to 83.5 wt.-%, based on the total weight of the second intermediate layer. Preferably, the weight proportion of the fifth heterophasic polypropylene in the second intermediate layer is in the range of 34±12 wt.-%, based on the total weight of the second intermediate layer; preferably 34±10 wt.-%, more preferably 34±8 wt.-%, even more preferably 34±6 wt.-%, most preferably 34±4 wt.-%.

[0170] In a more preferred embodiment, the weight proportion of the fifth heterophasic polypropylene in the second intermediate layer is in the range of 56±12 wt-%, based on the total weight of the second intermediate layer; preferably 56±10 wt-%, more preferably 56±8 wt-%, still more preferably 56±6 wt-%, most preferably 56±4 wt-%.

[0171] In a more preferred embodiment, the weight proportion of the fifth heterophasic polypropylene in the second intermediate layer is based on the total weight of the second intermediate layer.

[0172] - at least 35 wt. %, preferably at least 40 wt. %, more preferably at least 45 wt. %, even more preferably at least 50 wt. %, most preferably at least 55 wt. %; and / or

[0173] - at most 55 wt.-%, preferably at most 50 wt.-%, more preferably at most 45 wt.-%, even more preferably at most 40 wt.-%, most preferably at most 35 wt.-%.

[0174] Preferably, the weight proportion of the sixth heterophasic polypropylene in the second intermediate layer is in the range of 0 to 83.5 wt.-%, based on the total weight of the second intermediate layer. Preferably, the weight proportion of the sixth heterophasic polypropylene in the second intermediate layer is in the range of 50±12 wt.-%, based on the total weight of the second intermediate layer; preferably 50±10 wt.-%, more preferably 50±8 wt.-%, even more preferably 50±6 wt.-%, most preferably 50±4 wt.-%.

[0175] In a more preferred embodiment the weight proportion of the sixth heterophasic polypropylene in the second intermediate layer is in the range of 40±8 wt% based on the total weight of the second intermediate layer; preferably 40±6 wt%, more preferably 40±4 wt%, still more preferably 40±2 wt%.

[0176] In a more preferred embodiment, the weight proportion of the fourth heterophasic polypropylene in the first intermediate layer is based on the total weight of the first intermediate layer.

[0177] - at least 40% by weight, preferably at least 45% by weight, more preferably at least 50% by weight; and / or

[0178] - at most 50% by weight, preferably at most 45% by weight, more preferably at most 40% by weight.

[0179] In a more preferred embodiment, the release film according to the present invention has a first intermediate layer and a second intermediate layer in addition to the first surface layer and the second surface layer and the adhesion promoting layer, wherein

[0180] - the first intermediate layer is based on a mixture of a third heterophasic polypropylene and a fourth heterophasic polypropylene different therefrom;

[0181] - the second intermediate layer is based on a mixture of a fifth heterophasic polypropylene and a sixth heterophasic polypropylene different therefrom;

[0182] - the weight proportion of the third heterophasic polypropylene in the first intermediate layer is in the range of 34±12 wt.-%, based on the total weight of the first intermediate layer; preferably 34±10 wt.-%, more preferably 34±8 wt.-%, even more preferably 34±6 wt.-%, most preferably 34±4 wt.-%;

[0183] - the weight proportion of the fourth heterophasic polypropylene in the first intermediate layer is in the range of 48±6 wt.-%, based on the total weight of the first intermediate layer; preferably 48±4 wt.-%, more preferably 48±2 wt.-%;

[0184] - the weight proportion of the fifth heterophasic polypropylene in the second intermediate layer is in the range of 34±12 wt.-%, based on the total weight of the second intermediate layer; preferably 34±10 wt.-%, more preferably 34±8 wt.-%, even more preferably 34±6 wt.-%, most preferably 34±4 wt.-%;

[0185] - the weight proportion of the sixth heterophasic polypropylene in the second intermediate layer is in the range of 50±8 wt-%, based on the total weight of the second intermediate layer; preferably 50±6 wt-%, more preferably 50±4 wt-%, still more preferably 50±2 wt-%.

[0186] In a more preferred embodiment, the release film according to the present invention has a first intermediate layer and a second intermediate layer in addition to the first surface layer and the second surface layer and the adhesion promoting layer, wherein

[0187] - the first intermediate layer is based on a mixture of a third heterophasic polypropylene and a fourth heterophasic polypropylene different therefrom;

[0188] - the second intermediate layer is based on a mixture of a fifth heterophasic polypropylene and a sixth heterophasic polypropylene different therefrom;

[0189] - the weight proportion of the third heterophasic polypropylene in the first intermediate layer is in the range of 58±12 wt.-%, based on the total weight of the first intermediate layer; preferably 58±10 wt.-%, more preferably 58±8 wt.-%, even more preferably 58±6 wt.-%, most preferably 58±4 wt.-%;

[0190] - the weight proportion of the fourth heterophasic polypropylene in the first intermediate layer is in the range of 40±6 wt.-%, based on the total weight of the first intermediate layer; preferably 40±4 wt.-%, more preferably 40±2 wt.-%;

[0191] - the weight proportion of the fifth heterophasic polypropylene in the second intermediate layer is in the range of 56±12 wt.-%, based on the total weight of the second intermediate layer; preferably 56±10 wt.-%, more preferably 56±8 wt.-%, even more preferably 56±6 wt.-%, most preferably 56±4 wt.-%;

[0192] - the weight proportion of the sixth heterophasic polypropylene in the second intermediate layer is in the range of 40±8 wt-%, based on the total weight of the second intermediate layer; preferably 40±6 wt-%, more preferably 40±4 wt-%, still more preferably 40±2 wt-%.

[0193] In a preferred embodiment, the third heterophasic polypropylene in the first intermediate layer and / or the fifth heterophasic polypropylene in the second intermediate layer each independently has a melt flow rate MFR 230°C, 2.16 basis weight according to ISO 1133-1 of

[0194] - at least 0.2 g / 10 min; preferably at least 0.3 g / 10 min, more preferably at least 0.4 g / 10 min, even more preferably at least 0.5 g / 10 min; and / or

[0195] - at most 1.0 g / 10 min; preferably at most 0.9 g / 10 min, more preferably at most 0.8 g / 10 min, even more preferably at most 0.7 g / 10 min; and / or

[0196] - in the range of 0.6±0.3 g / 10 min; preferably 0.6±0.2 g / 10 min, more preferably 0.6±0.1 g / 10 min;

[0197] In a preferred embodiment the third heterophasic polypropylene in the first intermediate layer and / or the fifth heterophasic polypropylene in the second intermediate layer each independently has a DSC melting temperature according to ISO 11357-3 of

[0198] - at least 125°C; preferably at least 130°C, more preferably at least 135°C, even more preferably at least 140°C; and / or

[0199] - at most 165°C; preferably at most 155°C, more preferably at most 150°C, still more preferably at most 145°C; and / or

[0200] - In the range of 142±24°C; preferably 142±16°C, more preferably 142±8°C.

[0201] Heterophasic polypropylenes having such properties are known to the person skilled in the art and are commercially available, for example as Q 100F.

[0202] In a preferred embodiment, the fourth heterophasic polypropylene in the first intermediate layer and / or the sixth heterophasic polypropylene in the second intermediate layer each independently has a melt flow rate MFR 230°C, 2.16 kg / m2 according to ISO 1133-1 of

[0203] - at least 0.4 g / 10 min; preferably at least 0.5 g / 10 min, more preferably at least 0.6 g / 10 min, even more preferably at least 0.7 g / 10 min; and / or

[0204] - at most 1.3 g / 10 min; preferably at most 1.2 g / 10 min, more preferably at most 1.1 g / 1.0 min, even more preferably at most 0.9 g / 10 min; and / or

[0205] - in the range of 0.8±0.3 g / 10 min; preferably 0.8±0.2 g / 10 min, more preferably 0.8±0.1 g / 10 min;

[0206] In a preferred embodiment the fourth heterophasic polypropylene in the first intermediate layer and / or the sixth heterophasic polypropylene in the second intermediate layer each independently has a DSC melting temperature according to ISO 11357-3 of

[0207] - at least 120°C; preferably at least 125°C, more preferably at least 130°C, even more preferably at least 135°C; and / or

[0208] - at most 165°C; preferably at most 155°C, more preferably at most 150°C, still more preferably at most 145°C; and / or

[0209] - In the range of 140±24°C; preferably 140±16°C, more preferably 140±8°C.

[0210] Heterophasic polypropylenes having such properties are known to the person skilled in the art and are commercially available, for example as SA 233CF.

[0211] In a preferred embodiment of the isolation film according to the present invention

[0212] (i) the first heterophasic polypropylene in the second surface layer and the third heterophasic polypropylene in the first intermediate layer are identical; and / or

[0213] (ii) the first heterophasic polypropylene in the second surface layer and the fifth heterophasic polypropylene in the second intermediate layer are identical; and / or

[0214] (iii) the third heterophasic polypropylene in the first intermediate layer and the fifth heterophasic polypropylene in the second intermediate layer are identical; and / or

[0215] (iv) the fourth heterophasic polypropylene in the first intermediate layer and the sixth heterophasic polypropylene in the second intermediate layer are identical.

[0216] In a preferred embodiment of the isolation film according to the present invention

[0217] (i) the first heterophasic polypropylene in the second surface layer and the fourth heterophasic polypropylene in the first intermediate layer are different; and / or

[0218] (ii) the first heterophasic polypropylene in the second surface layer and the sixth heterophasic polypropylene in the second intermediate layer are different; and / or

[0219] (iii) the second heterophasic polypropylene in the second surface layer and the third heterophasic polypropylene in the first intermediate layer are different; and / or

[0220] (iv) the second heterophasic polypropylene in the second surface layer and the fourth heterophasic polypropylene in the first intermediate layer are different; and / or

[0221] (v) the second heterophasic polypropylene in the second surface layer and the fifth heterophasic polypropylene in the second intermediate layer are different; and / or

[0222] (vi) the second heterophasic polypropylene in the second surface layer and the sixth heterophasic polypropylene in the second intermediate layer are different; and / or

[0223] (vii) the third heterophasic polypropylene in the first intermediate layer and the sixth heterophasic polypropylene in the second intermediate layer are different; and / or

[0224] (viii) The fourth heterophasic polypropylene in the first intermediate layer and the fifth heterophasic polypropylene in the second intermediate layer are different.

[0225] Each layer of the isolation film according to the present invention can independently contain additives conventionally used in such films. Examples of such additives are pigments, dyes, lubricants, antistatic agents, fillers, nucleating agents, plasticizers, lubricants, stabilizers, ultraviolet absorbers, etc., which can be used in conventional amounts according to the present invention.

[0226] In a preferred embodiment of the release film according to the invention, the first intermediate layer and / or the second intermediate layer does not contain an antistatic agent.

[0227] In a preferred embodiment of the release film according to the invention, the first intermediate layer and / or the second intermediate layer independently comprises an antistatic agent. Suitable antistatic agents are known to those skilled in the art and are commercially available.

[0228] The weight proportion of antistatic agent is preferably in the range of 14±13% by weight, more preferably 14±10% by weight, even more preferably 14±7% by weight, most preferably 14±4% by weight, in each case independently of the total weight of the first or second interlayer.

[0229] Preferably, the antistatic agent is based on a polyether-polyamide block copolymer. Such antistatic agents are commercially available, for example as CESA-stat. For more detailed information, reference is made, for example, to DE 102010025938A1. Surprisingly, it was found that adding an antistatic agent to the first or second intermediate layer reduces the adhesion of dust.

[0230] In a preferred embodiment of the isolation film according to the present invention, both the first surface layer and the second surface layer do not contain a silicon compound.

[0231] Preferably, the release film according to the invention is planar, in particular non-embossed.

[0232] The release film according to the invention is preferably unoriented.

[0233] The isolation film according to the present invention generally has a longitudinal direction (MD) and a transverse direction (CD). These terms are known to those skilled in the art. "Longitudinal direction" is generally the direction in which the film is transported during production, and "transverse direction" is generally at a 90° angle to "longitudinal direction".

[0234] The release film according to the invention is preferably thermoplastic per se, ie it preferably consists essentially completely of thermoplastic polymers (and possible additives), ie it preferably contains no thermosetting plastics, reactive adhesives or the like.

[0235] The release film according to the invention is preferably thermoformable, preferably deep-drawable.

[0236] The term "deep-drawable" is known to the person skilled in the art. For the purposes of this description, "deep-drawable" in the sense of the present invention preferably means

[0237] - the tensile strength is preferably at least 10 N, or at least 12 N, or at least 14 N, or at least 16 N, or at least 18 N, or at least 20 N, or at least 22 N, or at least 24 N, or at least 26 N, or at least 28 N, or at least 30 N; in each case preferably in the machine direction (MD); or in the cross direction (CD); or in both the machine direction and the cross direction (MD and CD); and / or

[0238] - the modulus of elasticity is preferably at least 350 MPa, or at least 370 MPa, or at least 390 MPa, or at least 410 MPa, or at least 430 MPa, or at least 450 MPa, or at least 470 MPa; in each case preferably in the machine direction (MD); or in the cross direction (CD); or in both the machine direction and the cross direction (MD and CD); and / or

[0239] - the elongation at break is preferably at least 350%, or at least 375%, or at least 400%, or at least 425%, or at least 450%, or at least 475%, or at least 500%, or at least 525%, or at least 550%, or at least 575%, or at least 600%, or at least 625%, or at least 650%, or at least 675%, or at least 700%, or at least 725%, or at least 750%; in each case preferably in the machine direction (MD); or in the cross direction (CD); or in both machine direction and cross direction (MD and CD); and / or

[0240] - the tensile force at 25% elongation is preferably less than 15 N, or less than 14 N, or less than 13 N, or less than 12 N, or less than 11 N, or less than 10 N, or less than 9 N, or less than 8 N, or less than 7 N, or less than 6 N, or less than 5 N; in each case preferably in the machine direction (MD); or in the cross direction (CD); or in the machine direction and the cross direction (MD and CD);

[0241] In each case, the measurements were carried out in accordance with DIN EN ISO 527 on specimens with a width of 15 mm, with a clamping length of 100.00 mm, a preload of 100 mN and a test speed of 500 mm / min.

[0242] The barrier film according to the invention is preferably cold formable. The term "cold formable" preferably refers to formability at room temperature (23°C).

[0243] The release film according to the invention is preferably vacuum-tight. For the purposes of the description, "vacuum-tight" in the sense of the invention preferably means that the vacuum generated in the sealing sleeve of the release film is maintained for a sufficiently long period of time, with possible continuous evacuation of air, so that a molded part can be produced under vacuum from the semi-finished product located in the interior space. If the production of the molded part according to the invention includes, for example, curing of the plastic material in a vacuum and possibly with heating, the vacuum-tightness of the release film according to the invention is sufficient to maintain the vacuum in the interior space until the plastic material is at least partially, preferably completely, cured, with optional continuous evacuation of air.

[0244] Preferably, the air permeability of the barrier film is at most 2200 cm according to ISO 15105-1:2007. 3 mm / m 2 Skybar, more preferably up to 2100cm 3 mm / m 2 Tianba, even more preferably up to 2000cm 3 mm / m 2 Skybar, most preferably up to 1900cm 3 mm / m 2 Tianba, especially up to 1800cm3 mm / m 2 Preferably, the oxygen permeability and / or nitrogen permeability are also within the above ranges.

[0245] Preferably, the release film according to the invention has a total layer thickness in the range of 40±30 μm; preferably 40±25 μm, more preferably 40±20 μm, even more preferably 40±15 μm, still more preferably 40±10 μm, most preferably 40±5 μm.

[0246] Suitable methods for determining the total layer thickness of the separator and for determining the layer thickness of individual layers within the separator are known to the person skilled in the art. According to the invention, the determination is preferably carried out microscopically on sections, whereby the measured value is given as the average of a total of 10 measurements.

[0247] In a preferred embodiment, the release film according to the present invention is transparent. In the sense of the present invention, the term "transparent" means that the fiber composite plastic semi-finished product can be seen with the naked eye through the release film according to the present invention. Transparency is preferably quantified by means of a densitometer. Such methods are familiar to those skilled in the art. Preferably, haze can be measured as an optical value as a measure of transparency. The measurement of haze is preferably carried out according to ASTM test standard D1003-61m procedure A, after calibrating the measuring instrument using a haze standard with a haze between 0.3% and 34%. A suitable measuring instrument is, for example, a haze meter with an integrating sphere from Byk-Gardner, which allows the transmission of scattered light to be integrated within a solid angle of 8° to 160°. The isolation film according to the present invention preferably has a haze of less than 100%, more preferably less than 96%, even more preferably less than 92%, most preferably less than 88% and in particular less than 84% as measured by the above method; and / or a transparency of greater than 45%, preferably greater than 50%, more preferably greater than 55%, still more preferably greater than 60%, most preferably greater than 65%; and / or a clarity of greater than 8%, preferably greater than 10%, more preferably greater than 12%, still more preferably greater than 14%, most preferably greater than 16%.

[0248] In other preferred embodiments, the release film according to the invention is opaque.

[0249] The release film according to the invention can be produced by conventional methods for producing multilayer films, preferably extrusion processes, in particular blown film coextrusion or cast film extrusion, wherein blown film coextrusion is particularly preferred.

[0250] Another aspect of the invention relates to a method for producing a fiber composite plastic component from a curable fiber composite plastic semi-finished product, comprising the following steps:

[0251] (a) providing a mould for producing a fibre composite plastic part, the mould having a shape corresponding at least in one cross section to the shape of the fibre composite plastic part to be produced using the mould;

[0252] (b) introducing a release film according to the invention as described above into a mould, wherein the release film lines the mould at least in a cross section corresponding to the shape of the fibre composite plastic part to be produced with the mould; and wherein a first surface layer of the release film faces the mould;

[0253] (c) optionally deep drawing the release film;

[0254] (d) introducing the curable fiber composite plastic semi-finished product into the mold, wherein the second surface layer of the release film faces the curable fiber composite plastic semi-finished product;

[0255] (e) optionally closing and / or evacuating the mold;

[0256] (f) heating the mould to a temperature at which the curable fibre composite plastic semi-finished product cures; optionally under pressure;

[0257] (g) optionally cooling the solidified fiber composite plastic component;

[0258] (h) optionally removing the cured fiber composite plastic part together with the release film attached thereto from the mold; and

[0259] (i) Optionally removing the release film from the cured fiber composite plastic component.

[0260] In the production of the fiber composite plastic part, the fiber composite plastic semi-finished product impregnated with the plastic resin to be cured, preferably the epoxy resin to be cured, is introduced into the mold in step (d) and sealed in a vacuum-tight manner in step (e). By applying a vacuum, the release film according to the invention is compressed while compacting the fiber material. While maintaining the vacuum, the mold with the shaped laminate is heated in an autoclave to the curing temperature of the plastic resin to be cured and maintained for the entire curing time, which is usually several hours.

[0261] In addition to processing with an autoclave, it is also possible to process with press pressure or simply at atmospheric pressure (ie curing in an oven). Curing can also be achieved by microwave irradiation.

[0262] After the curing time and cooling in step (g), the fiber composite plastic component is removed from the mold in step (h) and packaged, preferably to exclude the influence of moisture, until final use.

[0263] Preferably, the fiber composite plastic component comprises another material selected from balsa wood, technical foam, glass nonwoven, carbon fibers, glass fibers and combinations thereof.

[0264] Preferably, the fiber composite plastic semi-finished product comprises a curable epoxy resin or a curable polyester resin; preferably a curable epoxy resin.

[0265] Preferably, the fiber composite plastic component is intended for use in a means of transport, preferably an aircraft, a spacecraft, a train or a motor vehicle, or for use in a wind turbine, preferably a rotor blade.

[0266] Another aspect of the invention relates to a fiber composite plastic component, to whose outer surface an insulating film according to the invention as described above is attached at least in sections and can be removed, preferably without leaving any residue, wherein the second surface layer of the insulating film faces the fiber composite plastic component.

[0267] At the same time, the fiber composite plastic component is preferably intended for use in a means of transport, preferably for an aircraft, a spacecraft, a train or a motor vehicle, or for a wind turbine, preferably for a rotor blade.

[0268] A further aspect of the invention relates to the use of the above-described separator film according to the invention as a separator film, preferably for producing a fiber composite plastic component, particularly preferably in the above-described method according to the invention.

[0269] Figure 1 A cross section of a release film (1) according to the present invention is shown, which has a schematic preferred layer structure, comprising a first surface layer (2), an adhesion promoting layer (3), a first intermediate layer (4), a second intermediate layer (5) and a second surface layer (6).

[0270] Figure 2 It is schematically shown how an isolation film (1) according to the invention is introduced into a mold (7) for producing a fiber composite plastic part, wherein the first surface layer (2) of the isolation film (1) faces the mold (7). A person skilled in the art will recognize that the isolation film (1) according to the invention generally does not have such a pronounced rigidity that it closes the mold (7) in a planar manner, as shown in the figure. On the contrary, the isolation film (1) according to the invention generally exhibits a certain flexibility, so that it can already adapt to the shape of the mold (7) to a certain extent without the need for special measures. However, according to the invention, the precise fit of the isolation film (1) to the mold (7) is preferably achieved only by deep drawing, for example after a vacuum has been applied between the mold (7) and the isolation film (1).

[0271] Figure 3 It is schematically shown how a fiber composite plastic component can be produced from a curable fiber composite plastic semi-finished product ( 8 ) using a release film ( 1 ) according to the invention. Figure 3 A corresponds to Figure 2 Arrangement shown, i.e. before deep drawing of the separator film. Figure 3 B shows the deep-drawn release film ( 1 ) in the mold ( 7 ). Figure 3 C shows how the curable fiber composite plastic semi-finished product (8) is applied to the release film (1), wherein the second surface side of the release film (1) faces the curable fiber composite plastic semi-finished product (8). Figure 3 D shows how the cured fiber composite semi-finished product together with the release film ( 1 ) attached thereto is removed from the mold ( 7 ). Figure 3 E shows how the release film (1) is removed from the cured fiber composite semi-finished product. Finally, Figure 3 E shows the finished, cured fiber composite plastic semi-finished product with its surface exposed.

[0272] List of Figure Numbers:

[0273] (1) Isolation film

[0274] (2) First surface layer

[0275] (3) Adhesion promoting layer

[0276] (4) First intermediate layer

[0277] (5) Second intermediate layer

[0278] (6) Second surface layer

[0279] (7) Molds for manufacturing fiber composite plastic parts

[0280] (8) Curable fiber composite plastic semi-finished products

[0281] The following examples are used to illustrate the present invention, but should not be construed in a restrictive manner:

[0282] Embodiment 1-3:

[0283] Three isolation membranes with the following structures and compositions were prepared:

[0284]

[0285]

[0286] All percentages are by weight.

[0287] The films according to Examples 1 and 2 showed no curling and were very flat. We examined the mechanical properties of these two films in more detail. The following table shows the measurement results of mechanical tests of the release films (Examples 1-2), each measured in the longitudinal direction (MD) and the transverse direction (CD), each determined according to DIN EN ISO 527 on a sample with a width of 15 mm; clamping length: 100.00 mm, preload: 100 mN, test speed: 500 mm / min:

[0288] Measurement results for elastic modulus, elongation at break, tensile and tensile strength, and thickness

[0289]

[0290] Tensile force and elongation measurement results

[0291] Example F 1% [N] F 2.5% [N] F 5% [N] F 10% [N] F 25% [N] Example 1 (MD) 2.8±0.2 5.9±0.1 7.7±0.1 9.5±0.2 11.5±0.3 Example 1 (CD) 3.5±0.0 6.2±0.0 7.7±0.0 8.9±0.1 9.3±0.1 Example 2 (MD) 2.5±0.1 4.5±0.3 6.1±0.4 7.9±0.5 1 0.3±0.6 Example 2 (CD) 2.4±0.2 4.4±0.2 5.7±0.3 6.8±0.3 7.2±0.3

[0292] Furthermore, the air permeability of the membranes was measured according to Example 1 and Example 2. The measurements were carried out according to ISO 15105-1 (2007-10) at 23° C. with air. The relative humidity was 0%. In each case, the flat side of the isolation membrane was facing the test gas (air). The test results are summarized in the following table:

[0293] Air permeability measurement results

[0294]

[0295] In addition, the transparency of the film was also measured according to Example 1 and Example 2. The measurement was performed according to ISO and ASTM. The measurement results are summarized in the following table.

[0296] Haze measurement results

[0297]

Claims

1. A multi-layer isolation film (1), comprising - a first surface layer (2) based on a mixture of a thermoplastic elastomer and a polyolefin; - an adhesion promoting layer (3); - an optional first intermediate layer (4); - an optional second intermediate layer (5); and - a second surface layer (6) based on at least one polypropylene or a propylene copolymer; The isolation film (1) has a total layer thickness in the range of 10 to 250 μm.

2. The release membrane (1) according to claim 1, wherein the thermoplastic elastomer in the first surface layer (2) is a thermoplastic polyester elastomer.

3. An isolation film (1) according to claim 1 or 2, wherein the thermoplastic elastomer in the first surface layer (2) has a DSC melting temperature according to ISO 11357-3 of at least 150°C; preferably at least 155°C, more preferably at least 160°C, still more preferably at least 165°C.

4. An isolation film (1) according to any one of the preceding claims, wherein the thermoplastic elastomer in the first surface layer (2) has a DSC melting temperature according to ISO 11357-3 of at most 190°C; preferably at most 185°C, more preferably at most 180°C, still more preferably at most 175°C.

5. An isolation film (1) according to any one of the preceding claims, wherein the thermoplastic elastomer in the first surface layer (2) has a DSC melting temperature in the range of 170±24°C according to ISO 11357-3; preferably 170±16°C, more preferably 170±8°C.

6. A release film (1) according to any one of the preceding claims, wherein the polyolefin in the first surface layer (2) is polyethylene or an ethylene copolymer; preferably LLDPE.

7. An isolation film (1) according to any of the preceding claims, wherein the polyolefin in the first surface layer (2) has a melt flow index MFI 190°C, 2.16 kg according to ISO 1133 of at least 0.7 g / 10 min; preferably at least 0.8 g / 10 min, more preferably at least 0.9 g / 10 min, still more preferably at least 1.0 g / 10 min.

8. An isolation film (1) according to any of the preceding claims, wherein the polyolefin in the first surface layer (2) has a melt flow index MFI 190°C, 2.16 kg according to ISO 1133 of at most 1.5 g / 10 min; preferably at most 1.4 g / 10 min, more preferably at most 1.3 g / 10 min, still more preferably at most 1.2 g / 10 min.

9. An isolation film (1) according to any of the preceding claims, wherein the polyolefin in the first surface layer (2) has a melt flow index MFI 190°C, 2.16 kg according to ISO 1133 in the range of 1.1±0.3 g / 10 min; preferably 1.1±0.2 g / 10 min, more preferably 1.1±0.1 g / 10 min.

10. The release film (1) according to any one of the preceding claims, wherein the polyolefin in the first surface layer (2) has a Vicat softening temperature according to ASTM D1525 of at least 96°C; preferably at least 98°C, more preferably at least 100°C, still more preferably at least 102°C.

11. The release film (1) according to any one of the preceding claims, wherein the polyolefin in the first surface layer (2) has a Vicat softening temperature according to ASTM D1525 of at most 112°C; preferably at most 110°C, more preferably at most 108°C, still more preferably at most 106°C.

12. The release film (1) according to any one of the preceding claims, wherein the polyolefin in the first surface layer (2) has a Vicat softening temperature in the range of 104±9°C according to ASTM D1525; preferably 104±6°C; more preferably 104±3°C.

13. The release film (1) according to any one of the preceding claims, wherein the polyolefin in the first surface layer (2) has a carbon fiber toughness according to ASTM D792 of at least 0.900 g / cm 3 Density; preferably at least 0.905g / cm 3 , more preferably at least 0.910 g / cm 3 , still more preferably at least 0.915 g / cm 3 .

14. The release film (1) according to any one of the preceding claims, wherein the polyolefin in the first surface layer (2) has a carbonyl content of at most 0.940 g / cm2 according to ASTM D792. 3 Density; preferably up to 0.935g / cm 3 , more preferably at most 0.930 g / cm 3 , still more preferably at most 0.925 g / cm 3 .

15. The release film (1) according to any one of the preceding claims, wherein the polyolefin in the first surface layer (2) has a molecular weight of 0.919 ± 0.020 g / cm 3 Density within the range; preferably 0.919±0.015g / cm 3 , more preferably 0.919±0.010g / cm 3 , still more preferably 0.919±0.005 g / cm 3 .

16. The separator (1) according to any one of the preceding claims, wherein in the first surface layer (2), the weight proportion of the thermoplastic elastomer is greater than the weight proportion of the polyolefin.

17. An isolation membrane (1) according to any one of the preceding claims, wherein the weight proportion of the thermoplastic elastomer in the first surface layer (2) is in the range of 72±25 weight % based on the total weight of the first surface layer (2); preferably 72±20 weight %, more preferably 72±15 weight %, even more preferably 72±10 weight %, and most preferably 72±5 weight %.

18. An isolation film (1) according to any of the preceding claims, wherein the weight proportion of the polyolefin in the first surface layer (2) is in the range of 10±9 weight % based on the total weight of the first surface layer (2); preferably 10±8 weight %, more preferably 10±7 weight %, still more preferably 10±6 weight %, and most preferably 10±5 weight %.

19. Release film (1) according to any of the preceding claims, wherein the at least one polypropylene or propylene copolymer in the second surface layer (6) is at least one heterophasic polypropylene.

20. An isolation film (1) according to any of the preceding claims, wherein the weight proportion of the at least one polypropylene or propylene copolymer in the second surface layer (6) is in the range of 88±12 weight % based on the total weight of the second surface layer (6); preferably 88±10 weight %, more preferably 88±8 weight %, even more preferably 88±6 weight %, and most preferably 88±4 weight %.

21. Release film (1) according to any of the preceding claims, wherein the at least one polypropylene or propylene copolymer in the second surface layer (6) is a mixture of a first heterophasic polypropylene and a second heterophasic polypropylene different therefrom.

22. An isolation film (1) according to claim 21, wherein the weight proportion of the first heterophasic polypropylene in the second surface layer (6) is in the range of 20±12 weight % based on the total weight of the second surface layer (6); preferably 20±10 weight %, more preferably 20±8 weight %, even more preferably 20±6 weight %, most preferably 20±4 weight %.

23. An isolation film (1) according to claim 21 or 22, wherein the weight proportion of the second heterophasic polypropylene in the second surface layer (6) is in the range of 68±12 weight % based on the total weight of the second surface layer (6); preferably 68±10 weight %, more preferably 68±8 weight %, still more preferably 68±6 weight %, most preferably 68±4 weight %.

24. Release film (1) according to any of claims 21 to 23, wherein the first heterophasic polypropylene has a lower melt flow rate than the second heterophasic polypropylene.

25. The release film (1) according to any of claims 21 to 24, wherein the first heterophasic polypropylene has a lower DSC melting temperature than the second heterophasic polypropylene.

26. The release film (1) according to any one of claims 21 to 25, wherein the first heterophasic polypropylene has a melt flow rate MFR 230°C, 2.16 kg according to ISO 1133-1 of at least 0.2 g / 10 min; preferably at least 0.3 g / 10 min, more preferably at least 0.4 g / 10 min, even more preferably at least 0.5 g / 10 min.

27. The release film (1) according to any one of claims 21 to 26, wherein the first heterophasic polypropylene has a melt flow rate MFR 230°C, 2.16 kg according to ISO 1133-1 of at most 1.0 g / 10 min; preferably at most 0.9 g / 10 min, more preferably at most 0.8 g / 10 min, still more preferably at most 0.7 g / 10 min.

28. The release film (1) according to any of claims 21 to 27, wherein the first heterophasic polypropylene has a melt flow rate MFR 230°C, 2.16 kg according to ISO 1133-1 in the range of 0.6±0.3 g / 10 min; preferably 0.6±0.2 g / 10 min, more preferably 0.6±0.1 g / 10 min.

29. The release film (1) according to any of claims 21 to 28, wherein the first heterophasic polypropylene has a DSC melting temperature according to ISO 11357-3 of at least 125°C; preferably at least 130°C, more preferably at least 135°C, still more preferably at least 140°C.

30. The release film (1) according to any of claims 21 to 29, wherein the first heterophasic polypropylene has a DSC melting temperature according to ISO 11357-3 of at most 165°C; preferably at most 155°C, more preferably at most 150°C, still more preferably at most 145°C.

31. The release film (1) according to any of claims 21 to 30, wherein the first heterophasic polypropylene has a DSC melting temperature according to ISO 11357-3 in the range of 142±24°C; preferably 142±16°C, more preferably 142±8°C.

32. The release film (1) according to any one of claims 21 to 31, wherein the second heterophasic polypropylene has a melt flow rate MFR 230°C, 2.16 kg according to ISO 1133-1 of at least 0.5 g / 10 min; preferably at least 0.6 g / 10 min, more preferably at least 0.7 g / 10 min, still more preferably at least 0.8 g / 10 min.

33. The release film (1) according to any one of claims 21 to 32, wherein the second heterophasic polypropylene has a melt flow rate MFR 230°C, 2.16 kg according to ISO 1133-1 of at most 1.2 g / 10 min; preferably at most 1.1 g / 10 min, more preferably at most 1.0 g / 10 min, still more preferably at most 0.9 g / 10 min.

34. The release film (1) according to any of claims 21 to 33, wherein the second heterophasic polypropylene has a melt flow rate MFR 230°C, 2.16 kg according to ISO 1133-1 in the range of 0.85±0.3 g / 10 min; preferably 0.85±0.2 g / 10 min, more preferably 0.85±0.1 g / 10 min.

35. The release film (1) according to any of claims 21 to 34, wherein the second heterophasic polypropylene has a DSC melting temperature according to ISO 11357-3 of at least 150°C; preferably at least 155°C, more preferably at least 160°C, still more preferably at least 165°C.

36. The release film (1) according to any of claims 21 to 34, wherein the second heterophasic polypropylene has a DSC melting temperature according to ISO 11357-3 of at most 185°C; preferably at most 180°C, more preferably at most 175°C, still more preferably at most 170°C.

37. The release film (1) according to any of claims 21 to 34, wherein the second heterophasic polypropylene has a DSC melting temperature according to ISO 11357-3 in the range of 166±24°C; preferably 166±16°C, more preferably 166±8°C.

38. The barrier film (1) according to any of the preceding claims, wherein the layer thickness of the second surface layer (6) is greater than the layer thickness of the first surface layer (2).

39. The barrier film (1) according to any of the preceding claims, wherein the first surface layer (2) has a layer thickness of at least 5 μm; preferably at least 6 μm, more preferably at least 7 μm, even more preferably at least 8 μm.

40. The barrier film (1) according to any of the preceding claims, wherein the layer thickness of the first surface layer (2) is at most 13 μm; preferably at most 12 μm, more preferably at most 11 μm, still more preferably at most 10 μm.

41. The barrier film (1) according to any of the preceding claims, wherein the layer thickness of the first surface layer (2) is in the range of 9±7 μm; preferably 9±5 μm, more preferably 9±3 μm.

42. The barrier film (1) according to any of the preceding claims, wherein the layer thickness of the second surface layer (6) is at least 6 μm; preferably at least 8 μm, more preferably at least 10 μm, even more preferably at least 12 μm.

43. The barrier film (1) according to any of the preceding claims, wherein the layer thickness of the second surface layer (6) is at most 22 μm; preferably at most 20 μm, more preferably at most 18 μm, still more preferably at most 16 μm.

44. The barrier film (1) according to any of the preceding claims, wherein the layer thickness of the second surface layer (6) is in the range of 14±12 μm; preferably 14±9 μm, more preferably 14±6 μm.

45. The barrier film (1) according to any of the preceding claims, which is thermoformable, preferably deep-drawable.

46. ​​The barrier film (1) according to any one of the preceding claims, which is cold formable.

47. The barrier membrane (1) according to any one of the preceding claims, which is vacuum-tight.

48. The release film (1) according to any one of the preceding claims, wherein the adhesion promoting layer (3) is arranged between the first surface layer (2) and the first intermediate layer (4).

49. The release film (1) according to any one of the preceding claims, wherein the adhesion promoting layer (3) is directly adjacent to the first surface layer (2).

50. The release film (1) according to any one of the preceding claims, wherein the adhesion promoting layer (3) is directly adjacent to the first intermediate layer (4).

51. Release film (1) according to any one of the preceding claims, wherein the adhesion promoting layer (3) is based on ethylene-acrylate copolymers.

52. The release film (1) according to claim 51, wherein the ethylene-acrylate copolymer has a melt flow index MFI 190°C, 2.16 kg according to ISO 1133 of at least 1.6 g / 10 min; preferably at least 1.7 g / 10 min, more preferably at least 1.8 g / 10 min, still more preferably at least 1.9 g / 10 min.

53. An isolation film (1) according to claim 51 or 52, wherein the ethylene-acrylate copolymer has a melt flow index MFI 190°C, 2.16 kg according to ISO 1133 of at most 2.4 g / 10 min; preferably at most 2.3 g / 10 min, more preferably at most 2.2 g / 10 min, still more preferably at most 2.1 g / 10 min.

54. The release film (1) according to any one of claims 51 to 53, wherein the ethylene-acrylate copolymer has a melt flow index MFI 190°C, 2.16 kg according to ISO 1133 in the range of 2.0±0.3 g / 10 min; preferably 2.0±0.2 g / 10 min, more preferably 2.0±0.1 g / 10 min.

55. The release film (1) according to any one of claims 51 to 54, wherein the ethylene-acrylate copolymer has a DSC melting temperature according to ISO 11357-3 of at least 75°C; preferably at least 80°C, more preferably at least 85°C, still more preferably at least 90°C.

56. The release film (1) according to any one of claims 51 to 55, wherein the ethylene-acrylate copolymer has a DSC melting temperature according to ISO 11357-3 of at most 110°C; preferably at most 105°C, more preferably at most 100°C, still more preferably at most 95°C.

57. The release film (1) according to any one of claims 51 to 56, wherein the ethylene-acrylate copolymer has a DSC melting temperature according to ISO 11357-3 in the range of 91±12°C; preferably 91±8°C, more preferably 91±4°C.

58. The release film (1) according to any one of claims 51 to 57, wherein the ethylene-acrylate copolymer has a Vicat softening temperature according to ASTM D1525 of at least 40°C; preferably at least 42°C, more preferably at least 44°C, still more preferably at least 46°C.

59. The release film (1) according to any one of claims 51 to 58, wherein the ethylene-acrylate copolymer has a Vicat softening temperature according to ASTM D1525 of at most 65°C; preferably at most 60°C, more preferably at most 55°C, still more preferably at most 50°C.

60. The release film (1) according to any one of claims 51 to 59, wherein the ethylene-acrylate copolymer has a Vicat softening temperature according to ASTM D1525 in the range of 48±12°C; preferably 48±8°C, more preferably 48±4°C.

61. An isolation film (1) according to any one of claims 51 to 60, wherein the weight proportion of the ethylene-acrylate copolymer in the adhesion promoting layer (3) is at least 75 weight % based on the total weight of the adhesion promoting layer (3); preferably at least 80 weight %, more preferably at least 85 weight %, still more preferably at least 90 weight %, and most preferably at least 95 weight %.

62. The release film (1) according to any of the preceding claims, wherein the layer thickness of the adhesion promoting layer (3) is at least 0.5 μm; preferably at least 1.0 μm, more preferably at least 1.5 μm, still more preferably at least 2.0 μm.

63. The release film (1) according to any of the preceding claims, wherein the layer thickness of the adhesion-promoting layer (3) is at most 7 μm; preferably at most 6 μm, more preferably at most 5 μm, still more preferably at most 4 μm.

64. The release film (1) according to any of the preceding claims, wherein the layer thickness of the adhesion-promoting layer (3) is in the range of 3±2 μm; preferably 3±1 μm.

65. The barrier film (1) according to any of the preceding claims, wherein the first intermediate layer (4) has a greater layer thickness than the second intermediate layer (5).

66. The release film (1) according to any of the preceding claims, wherein the first intermediate layer (4) is arranged between the adhesion promoting layer (3) and the second intermediate layer (5).

67. The release film (1) according to any one of the preceding claims, wherein the first intermediate layer (4) is directly adjacent to the adhesion promoting layer (3).

68. The barrier film (1) according to any one of the preceding claims, wherein the first intermediate layer (4) is directly adjacent to the second intermediate layer (5).

69. The barrier film (1) according to any of the preceding claims, wherein the first intermediate layer (4) has a layer thickness of at least 5 μm; preferably at least 6 μm, more preferably at least 7 μm, even more preferably at least 8 μm.

70. The barrier film (1) according to any of the preceding claims, wherein the layer thickness of the first intermediate layer (4) is at most 16 μm; preferably at most 14 μm, more preferably at most 12 μm, still more preferably at most 10 μm.

71. The barrier film (1) according to any of the preceding claims, wherein the layer thickness of the first intermediate layer (4) is in the range of 9±8 μm; preferably 9±6 μm, more preferably 9±4 μm.

72. The barrier film (1) according to any of the preceding claims, wherein the second intermediate layer (5) is arranged between the first intermediate layer (4) and the second surface layer (6).

73. The barrier film (1) according to any of the preceding claims, wherein the second intermediate layer (5) is directly adjacent to the first intermediate layer (4).

74. The barrier film (1) according to any of the preceding claims, wherein the second intermediate layer (5) is directly adjacent to the second surface layer (6).

75. The barrier film (1) according to any of the preceding claims, wherein the layer thickness of the second intermediate layer (5) is at least 1 μm; preferably at least 2 μm, more preferably at least 3 μm, even more preferably at least 4 μm.

76. The barrier film (1) according to any of the preceding claims, wherein the layer thickness of the second intermediate layer (5) is at most 9 μm; preferably at most 8 μm, more preferably at most 7 μm, still more preferably at most 6 μm.

77. The barrier film (1) according to any of the preceding claims, wherein the layer thickness of the second intermediate layer (5) is in the range of 5±4 μm; preferably 5±3 μm, more preferably 5±2 μm.

78. The barrier film (1) according to any of the preceding claims, wherein the first intermediate layer (4) is based on at least one polypropylene or propylene copolymer; preferably on at least one heterophasic polypropylene; more preferably on a mixture of a third heterophasic polypropylene and a fourth heterophasic polypropylene different therefrom.

79. An isolation film (1) according to claim 78, wherein the weight proportion of the third heterophasic polypropylene in the first intermediate layer (4) is in the range of 34±12 weight % based on the total weight of the first intermediate layer (4); preferably 34±10 weight %, more preferably 34±8 weight %, even more preferably 34±6 weight %, most preferably 34±4 weight %; or is in the range of 58±12 weight % based on the total weight of the first intermediate layer; preferably 58±10 weight %, more preferably 58±8 weight %, even more preferably 58±6 weight %, most preferably 58±4 weight %.

80. An isolation film (1) according to claim 78 or 79, wherein the weight proportion of the fourth heterophasic polypropylene in the first intermediate layer (4) is in the range of 48±12 weight % based on the total weight of the first intermediate layer (4); preferably 48±10 weight %, more preferably 48±8 weight %, even more preferably 48±6 weight %, most preferably 48±4 weight %; or in the range of 40±6 weight % based on the total weight of the first intermediate layer; preferably 40±4 weight %, more preferably 40±2 weight %.

81. The barrier film (1) according to any of the preceding claims, wherein the second intermediate layer (5) is based on at least one polypropylene or propylene copolymer; preferably on at least one heterophasic polypropylene; more preferably on a mixture of a fifth heterophasic polypropylene and a sixth heterophasic polypropylene different therefrom.

82. An isolation film (1) according to claim 81, wherein the weight proportion of the fifth heterophasic polypropylene in the second intermediate layer (5) is in the range of 34±12 weight % based on the total weight of the second intermediate layer (5); preferably 34±10 weight %, more preferably 34±8 weight %, even more preferably 34±6 weight %, most preferably 34±4 weight %; or is in the range of 56±12 weight % based on the total weight of the second intermediate layer; preferably 56±10 weight %, more preferably 56±8 weight %, even more preferably 56±6 weight %, most preferably 56±4 weight %.

83. An isolation film (1) according to claim 81 or 82, wherein the weight proportion of the sixth heterophasic polypropylene in the second intermediate layer (5) is in the range of 50±12 weight % based on the total weight of the second intermediate layer (5); preferably 50±10 weight %, more preferably 50±8 weight %, even more preferably 50±6 weight %, most preferably 50±4 weight %; or is in the range of 40±8 weight % based on the total weight of the second intermediate layer; preferably 40±6 weight %, more preferably 40±4 weight %, even more preferably 40±2 weight %.

84. The release film (1) according to any of the claims 78 to 83, wherein in the first intermediate layer (4) the third heterophasic polypropylene has a lower melt flow rate than the fourth heterophasic polypropylene.

85. The release film (1) according to any of claims 78 to 84, wherein in the first intermediate layer (4) the third heterophasic polypropylene has a higher DSC melting temperature than the fourth heterophasic polypropylene.

86. The release film (1) according to any of the claims 81 to 85, wherein in the second intermediate layer (5) the fifth heterophasic polypropylene has a lower melt flow rate than the sixth heterophasic polypropylene.

87. The release film (1) according to any of the claims 81 to 86, wherein in the second intermediate layer (5) the fifth heterophasic polypropylene has a higher DSC melting temperature than the sixth heterophasic polypropylene.

88. The isolation film (1) according to any one of claims 78 to 87, wherein the third heterophasic polypropylene in the first intermediate layer (4) and / or the fifth heterophasic polypropylene in the second intermediate layer (5) each independently has a melt flow rate MFR 230°C, 2.16kg according to ISO 1133-1 of at least 0.2 g / 10 min; preferably at least 0.3 g / 10 min, more preferably at least 0.4 g / 10 min, even more preferably at least 0.5 g / 10 min.

89. The isolation film (1) according to any one of claims 78 to 88, wherein the third heterophasic polypropylene in the first intermediate layer (4) and / or the fifth heterophasic polypropylene in the second intermediate layer (5) each independently has a melt flow rate MFR 230°C, 2.16 kg according to ISO 1133-1 of at most 1.0 g / 10 min; preferably at most 0.9 g / 10 min, more preferably at most 0.8 g / 10 min, still more preferably at most 0.7 g / 10 min.

90. The isolation film (1) according to any one of claims 78 to 89, wherein the third heterophasic polypropylene in the first intermediate layer (4) and / or the fifth heterophasic polypropylene in the second intermediate layer (5) each independently has a melt flow rate MFR 230°C, 2.16 kg according to ISO 1133-1 in the range of 0.6±0.3 g / 10 min; preferably 0.6±0.2 g / 10 min, more preferably 0.6±0.1 g / 10 min.

91. The isolation film (1) according to any one of claims 78 to 90, wherein the third heterophasic polypropylene in the first intermediate layer (4) and / or the fifth heterophasic polypropylene in the second intermediate layer (5) each independently has a DSC melting temperature according to ISO 11357-3 of at least 125°C; preferably at least 130°C, more preferably at least 135°C, still more preferably at least 140°C.

92. The isolation film (1) according to any one of claims 78 to 91, wherein the third heterophasic polypropylene in the first intermediate layer (4) and / or the fifth heterophasic polypropylene in the second intermediate layer (5) each independently has a DSC melting temperature according to ISO 11357-3 of at most 165°C; preferably at most 155°C, more preferably at most 150°C, still more preferably at most 145°C.

93. The isolation film (1) according to any one of claims 78 to 92, wherein the third heterophasic polypropylene in the first intermediate layer (4) and / or the fifth heterophasic polypropylene in the second intermediate layer (5) each independently has a DSC melting temperature in the range of 142±24°C according to ISO 11357-3; preferably 142±16°C, more preferably 142±8°C.

94. The isolation film (1) according to any one of claims 78 to 93, wherein the fourth heterophasic polypropylene in the first intermediate layer (4) and / or the sixth heterophasic polypropylene in the second intermediate layer (5) each independently has a melt flow rate MFR 230°C, 2.16 kg according to ISO 1133-1 of at least 0.4 g / 10 min; preferably at least 0.5 g / 10 min, more preferably at least 0.6 g / 10 min, still more preferably at least 0.7 g / 10 min.

95. The isolation film (1) according to any one of claims 78 to 94, wherein the fourth heterophasic polypropylene in the first intermediate layer (4) and / or the sixth heterophasic polypropylene in the second intermediate layer (5) each independently has a melt flow rate MFR 230°C, 2.16 kg according to ISO 1133-1 of at most 1.3 g / 10 min; preferably at most 1.2 g / 10 min, more preferably at most 1.1 g / 1.0 min, still more preferably at most 0.9 g / 10 min.

96. The isolation film (1) according to any one of claims 78 to 95, wherein the fourth heterophasic polypropylene in the first intermediate layer (4) and / or the sixth heterophasic polypropylene in the second intermediate layer (5) each independently has a melt flow rate MFR 230°C, 2.16 kg according to ISO 1133-1 in the range of 0.8±0.3 g / 10 min; preferably 0.8±0.2 g / 10 min, more preferably 0.8±0.1 g / 10 min.

97. The isolation film (1) according to any one of claims 78 to 96, wherein the fourth heterophasic polypropylene in the first intermediate layer (4) and / or the sixth heterophasic polypropylene in the second intermediate layer (5) each independently has a DSC melting temperature according to ISO 11357-3 of at least 120°C; preferably at least 125°C, more preferably at least 130°C, still more preferably at least 135°C.

98. The release film (1) according to any one of claims 78 to 97, wherein the fourth heterophasic polypropylene in the first intermediate layer (4) and / or the sixth heterophasic polypropylene in the second intermediate layer (5) each independently has a DSC melting temperature according to ISO 11357-3 of at most 165°C; preferably at most 155°C, more preferably at most 150°C, still more preferably at most 145°C.

99. The isolation film (1) according to any one of claims 78 to 98, wherein the fourth heterophasic polypropylene in the first intermediate layer (4) and / or the sixth heterophasic polypropylene in the second intermediate layer (5) each independently has a DSC melting temperature in the range of 140±24°C according to ISO 11357-3; preferably 140±16°C, more preferably 140±8°C.

100. The release film (1) according to any of claims 78 to 99, wherein the first heterophasic polypropylene in the second surface layer (6) and the third heterophasic polypropylene in the first intermediate layer (4) are identical.

101. The release film (1) according to any of claims 78 to 100, wherein the first heterophasic polypropylene in the second surface layer (6) and the fifth heterophasic polypropylene in the second intermediate layer (5) are identical.

102. The release film (1) according to any of claims 78 to 101, wherein the third heterophasic polypropylene in the first intermediate layer (4) and the fifth heterophasic polypropylene in the second intermediate layer (5) are identical.

103. The release film (1) according to any of claims 78 to 102, wherein the fourth heterophasic polypropylene in the first intermediate layer (4) and the sixth heterophasic polypropylene in the second intermediate layer (5) are identical.

104. The release film (1) according to any of claims 78 to 103, wherein the first heterophasic polypropylene in the second surface layer (6) and the fourth heterophasic polypropylene in the first intermediate layer (4) are different.

105. The release film (1) according to any of claims 78 to 104, wherein the first heterophasic polypropylene in the second surface layer (6) and the sixth heterophasic polypropylene in the second intermediate layer (5) are different.

106. Release film (1) according to any of claims 78 to 105, wherein the second heterophasic polypropylene in the second surface layer (6) and the third heterophasic polypropylene in the first intermediate layer (4) are different.

107. Release film (1) according to any of claims 78 to 106, wherein the second heterophasic polypropylene in the second surface layer (6) and the fourth heterophasic polypropylene in the first intermediate layer (4) are different.

108. The release film (1) according to any of claims 78 to 107, wherein the second heterophasic polypropylene in the second surface layer (6) and the fifth heterophasic polypropylene in the second intermediate layer (5) are different.

109. Release film (1) according to any of claims 78 to 108, wherein the second heterophasic polypropylene in the second surface layer (6) and the sixth heterophasic polypropylene in the second intermediate layer (5) are different.

110. The release film (1) according to any of claims 78 to 109, wherein the third heterophasic polypropylene in the first intermediate layer (4) and the sixth heterophasic polypropylene in the second intermediate layer (5) are different.

111. The release film (1) according to any of claims 78 to 110, wherein the fourth heterophasic polypropylene in the first intermediate layer (4) and the fifth heterophasic polypropylene in the second intermediate layer (5) are different.

112. The isolation film (1) according to any of the preceding claims, having a total layer thickness in the range of 40±30 μm; preferably 40±25 μm, more preferably 40±20 μm, even more preferably 40±15 μm, most preferably 40±10 μm.

113. The release film (1) according to any of the preceding claims, wherein the first intermediate layer (4) comprises an antistatic agent.

114. The release film (1) according to any of the preceding claims, wherein the second intermediate layer (5) comprises an antistatic agent.

115. An isolation film (1) according to claim 113 or 114, wherein the weight proportion of the antistatic agent is in each case independently of one another in the range of 14±13 weight % based on the total weight of the first intermediate layer (4) or the second intermediate layer (5).

116. Release film (1) according to any one of claims 113 to 115, wherein the antistatic agent is based on a polyether-polyamide block copolymer.

117. The barrier film (1) according to any of the preceding claims, wherein both the first surface layer (2) and the second surface layer (6) are free of silicon compounds.

118. Use of the barrier film (1) according to any of the preceding claims as a barrier film.

119. The use according to claim 118 for producing a fiber composite plastic component from a curable fiber composite plastic semi-finished product (8).

120. A method for producing a fiber composite plastic component from a curable fiber composite plastic semi-finished product (8), comprising the following steps: (a) providing a mould (7) for producing a fibre composite plastic part, said mould (7) having a shape corresponding at least in one cross section to the shape of the fibre composite plastic part to be produced using said mould (7); (b) introducing a release film (1) according to any one of claims 1 to 46 into the mould (7), wherein the release film (1) lines the mould (7) at least in a cross section corresponding to the shape of the fibre composite plastic part to be produced with the mould (7); and wherein the first surface layer (2) of the release film (1) faces the mould (7); (c) optionally deep drawing the separator (1); (d) introducing the curable fiber composite plastic semi-finished product (8) into the mold (7), wherein the second surface layer (6) of the release film (1) faces the curable fiber composite plastic semi-finished product (8); (e) optionally closing and / or evacuating the mold (7); optionally deep-stretching the isolation film (1); (f) heating the mould (7) to a temperature at which the curable fibre composite plastic semi-finished product (8) cures; optionally under pressure; (g) optionally cooling the solidified fiber composite plastic part; (h) optionally removing the cured fiber composite plastic component together with the release film (1) attached thereto from the mold (7); and (i) Optionally removing the release film (1) from the cured fiber composite plastic component.

121. The method of claim 120, wherein the fiber composite plastic component comprises another material selected from the group consisting of balsa wood, engineered foam, non-woven glass, carbon fiber, fiberglass, and combinations thereof.

122. The method according to any one of claims 120 or 121, wherein the fiber composite plastic component is intended for use in a means of transport, preferably an aircraft, a spacecraft, a train or a motor vehicle, or for use in a wind turbine, preferably a rotor blade.

123. The method according to any one of claims 120 to 122, wherein the curable fiber composite plastic semi-finished product comprises a curable epoxy resin or a curable polyester resin; preferably a curable epoxy resin.

124. A fiber composite plastic component, wherein an isolation membrane (1) according to any one of claims 1 to 117 is attached to its outer surface at least in a partial area and can be removed therefrom, wherein the second surface layer (6) of the isolation membrane (1) faces the fiber composite plastic component.

125. Use of a barrier film (1) according to any one of claims 1 to 117 in a method according to any one of claims 120 to 123.

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