Barrier layer against migration of a substance, electrical conductor, method for manufacturing a coated cable and use of polyethylene furanoate as a barrier layer

Abstract

Barrier layer (101) against migration of a substance, wherein the barrier layer (101) is arranged in a cable (121, 123) and / or around an electrical conductor (105, 107, 109, 111), and the barrier layer (101) comprises or consists of polyethylene furanoate, characterized in that the barrier layer (101) is manufactured by extrusion together with a sheath layer (103) in one operation, such that the barrier layer (101) is permanently bonded to the sheath layer (103).

Description

[0001] The invention relates to a barrier layer against the migration of a substance, wherein the barrier layer is arranged in a cable and / or around an electrical conductor. Furthermore, the invention relates to an electrical conductor for transmitting energy and / or information, a cable for transmitting energy and / or information, a method for manufacturing a coated cable using an extrusion device, and the use of polyethylene furanoate as a barrier layer.

[0002] Various barrier layers are used to prevent the migration of substances into a cable or through a hose into the environment. For example, an aluminum layer is used around an electrical conductor in cables to prevent moisture from penetrating the conductor. However, such an aluminum layer has the disadvantage that it requires separate welding in an additional step. Furthermore, due to its rigid properties, aluminum makes the conductor and the cable inflexible. Consequently, a cable with an aluminum barrier layer can only withstand a limited number of bending cycles, typically a few thousand.

[0003] Furthermore, fluoropolymers are known for their use as barrier layers. However, fluoropolymers have the disadvantage of requiring a very high melting point and therefore processing temperature compared to other common plastics used in cable and / or hose manufacturing. Because fluoropolymers require a processing temperature that is too high compared to the other plastics used, at which the other plastics would already thermally decompose, a permanent bond with the other plastics is not possible.

[0004] Barrier layers made of polyethylene terephthalate (PET) are also known, but PET only has moderate barrier properties against migration and is particularly unsuitable for conveying acidic substances in hoses.

[0005] Due to these disadvantages of the state of the art, there is no barrier for various migrating substances such as water, oxygen, carbon dioxide, plasticizers and / or chemical compounds that has a sufficiently closed layer against the surrounding or conveyed medium and, on the other hand, prevents migration itself and does not impair the flexibility of the coated product.

[0006] WO 2015 / 066 570 A1 discloses a three-layer heat-shrinkable film for food packaging, wherein the first outer film layer comprises polyester, for example polyethylene furanoate (PEF), and the second inner layer serves as an oxygen barrier.

[0007] US 2017 / 0334120A1 describes a preform for stretch blow molding of a plastic container, wherein the preform consists of polyethylene furanoate with a certain viscosity at least in some places.

[0008] US 2016 / 0089228A1 relates to a catheter for medical use, wherein a guidewire with an integrated embolic filter has an outer sheath. The outer sheath may have a coating, for example polyethylene furanoate, which allows relative movement between the outer sheath, the guidewire, and an internal part of a patient's body.

[0009] EP 1 905 575 A1 discloses a stand-up pouch for food packaging, which is produced by blown film extrusion using a multilayer film.

[0010] The generic patent DE 10 2013 223 496 A1 relates to industrial adhesive tapes for the production of cable harnesses by wrapping and bundling a large number of electrical conductors. The bio-based polymer polyethylene furanoate (PEF) is described as a carrier material for single- and double-sided adhesive tapes and additionally for the production of release liners, covering material, and / or separating material. For this purpose, PEF is used in the form of sheet elements and / or fiber structures.

[0011] DE 10 2013 205 673 A1 also describes an adhesive tape with pressure-sensitive adhesive and a carrier, in which the pressure-sensitive adhesive layer is arranged on a surface element and the surface element has polyethylene furanoate (PEF).

[0012] CN 2 05 541 997 U claims an aluminum-plastic composite tape for use in industrial optical cables, comprising an aluminum strip on which an EAA (ethylene acrylic acid) film is arranged. A supporting mesh belt layer is arranged on the back of the aluminum strip, while a PEF fiber layer is arranged on the opposite EAA film, which, like the mesh belt layer, is surrounded by a plastic film composite layer.

[0013] US 5 912 436 A discloses a co-extruded, three-layer electrical conductor cable with insulation featuring low moisture absorption, low emission of toxic gases and smoke, and high flame resistance, and a corresponding method involving the simultaneous extrusion of three layers in only one extrusion head, wherein the cable has a three-layer insulating material around the electrical conductor, comprising an inner layer and an outer layer of modified polyvinyl chloride (PVC) compounds and an intermediate layer of modified polyethylene as a barrier against water.

[0014] The purpose of the invention is to improve the state of the art.

[0015] The problem is solved by a barrier layer against migration of a substance, wherein the barrier layer is arranged in a cable and / or around an electrical conductor, and the barrier layer comprises or consists of polyethylene furanoate, wherein the barrier layer is manufactured by extrusion together with a sheathing layer in one operation, so that the barrier layer is permanently bonded to the sheathing layer.

[0016] A barrier layer containing or consisting of polyethylene furanoate (PEF), also known as polyethylene dicarboxyfuranoate, forms a closed layer against the surrounding medium or the medium being conveyed, and also prevents the migration of various substances through PEF itself.

[0017] It is particularly advantageous that the dense, closed PEF barrier layer is simultaneously flexible, allowing a cable to undergo a high number of bending cycles, ranging from a few thousand to a few million bending cycles.

[0018] In particular, PEF provides a ten times better barrier against oxygen than PET, a four times better barrier against carbon dioxide than PET, and an approximately twice better barrier against water than PET.

[0019] Furthermore, PEF is a bio-based polymer and 100% recyclable.

[0020] A key aspect of the invention is that the use of the polymer polyethylene furanoate (PEF) provides a closed, dense barrier layer which is nevertheless flexible and thus does not restrict the use of cables and hoses despite their frequent flexural stresses. Furthermore, the processing conditions for PEF are similar to those of standard materials used in cable and / or hose manufacturing.

[0021] The following terms will be explained: A "barrier layer" is, in particular, a layer that, as a closed layer, forms a barrier against an surrounding and / or conveyed medium and itself prevents the migration of certain substances. A barrier layer protects an adjacent layer, the products and / or components located beneath it, and / or the environment from harmful influences. A barrier layer can, in particular, protect against environmental effects, such as the ingress of oxygen and / or water into the electrical conductor of a cable, or process-related effects, such as the migration of a conveyed substance from a hose into the environment. The barrier layer is, in particular, made of or contains PEF.

[0022] The term "migration" refers in particular to the movement of a substance into and / or through a material, plastic and / or into the surrounding medium.

[0023] A "substance" is, in particular, a gaseous, liquid, and / or solid substance that can migrate through the material(s) of a cable and / or hose. Substances include, in particular, water, oxygen, carbon dioxide, plasticizers, chemical compounds, and / or chemical mixtures, such as hydraulic fluid.

[0024] A "cable" is defined in particular as a single- or multi-core bundle of conductors (individual wires) sheathed with one or more insulating materials, used for the transmission of energy and / or information. A cable can be electrical or optical. In a multi-core cable, the conductors are each sheathed and insulated from one another. A cable can also be a precursor to a cable.

[0025] An "electrical conductor" is, in particular, a medium that has a high density of freely moving charge carriers and therefore good electrical conductivity, as well as the lowest possible electrical resistance, making it suitable for transporting charged particles (electric current). An electrical conductor is, in particular, an insulated wire or strand. A "wire" is, in particular, a thin, long, and / or flexible metal with a circular cross-section. However, a wire can also be a flat, square, or profile wire. A wire is, in particular, made of copper, aluminum, or a copper alloy. A "strand" is an electrical conductor consisting of thin individual wires and is, in particular, easily bendable. A strand contains, in particular, copper. The individual wires of the strand are, in particular, enclosed by a common insulating sheath (stranded wire).When several stranded wires are combined in a single cable, they are called conductors. A stranded wire has a thickness of 0.04 mm to 4 mm.

[0026] A "core" is, in particular, a single conductor within a bundle of a cable. A core typically has a conductor material of copper, aluminum, silver, steel, and / or lead. A core typically has a thickness of 0.1 mm to 15 mm.

[0027] A "hose" is, in particular, a flexible, elongated hollow body with a defined cross-section, which contains and / or carries a medium inside, such as hydraulic fluid or compressed air. Various cables can also be bundled together within a hose. A hose can be, in particular, a corrugated hose, corrugated tube, and / or smooth hose.

[0028] Polyethylene furanoate is a plastic based on 2,5-furandicarboxylic acid. The reaction of 2,5-furandicarboxylic acid with ethylene glycol produces the polyester polyethylene furanoate (PEF), which is also known as polyethylene dicarboxylfuranoate. Polyethylene furanoate is a bio-based polymer and is 100% recyclable. Specifically, polyethylene furanoate has a glass transition temperature of 86°C and a melting point of 235°C.

[0029] According to the invention, the barrier layer is manufactured by extrusion together with a shell layer in one operation, so that the barrier layer is permanently bonded to the shell layer.

[0030] It is particularly advantageous that the barrier layer and the jacket layer are manufactured in the same extrusion head of an extrusion machine in a single operation.

[0031] Because the manufacturing process takes place in one operation at the same and / or similar temperatures, the barrier layer and the shell layer are permanently bonded during extrusion, provided they are in direct contact with each other.

[0032] Consequently, an additional step for applying a barrier layer is eliminated. Furthermore, the permanent bond between the barrier layer and the casing layer creates a closed, integrated layer, preventing, for example, the accumulation of moisture between the casing layer and the barrier layer.

[0033] Extrusion refers specifically to the pressing of a molding compound through a die to form an extruded part. Extrusion is particularly useful for sheathing and / or coating wires, cable components, strands, and / or electrical conductors. It can also be used to manufacture hoses. Extrusion is typically carried out using an extrusion unit at a pressure of 10 bar to 1,500 bar and a temperature of 10°C to 150°C.

[0034] A "sheath layer" is, in particular, an outer layer surrounding a wire, cable component, strand, and / or cable. The sheath layer serves primarily to insulate and / or shield the wire, cable component, or strand, and / or, as a cable sheath, to protect the cable from external influences and / or to provide shielding. A cable can have an outer sheath layer (the cable sheath itself) and / or one or more inner sheath layers surrounding the respective electrical conductors (wire, strand, cable component). The sheath layer typically contains plastics such as polyolefins, polyurethane, polyvinyl chloride, polystyrene, polytetrafluoroethylene (PTFE), and / or silicone.

[0035] The term "permanently bonded" is understood to mean, in particular, that the barrier layer and the sheathing layer do not separate from each other during the entire service life and / or operating time of a cable, electrical conductor and / or hose.

[0036] To provide sufficient layer thickness to prevent migration and application-specific flexural flexibility, the barrier layer has a thickness in the range of 0.01 mm to 10 mm, preferably from 0.05 mm to 1 mm.

[0037] Therefore, due to its superior retention properties, the PEF barrier layer can be made thinner than a PET barrier layer. This allows for a reduction in the weight and material thickness of a cable and / or hose, further improving bending flexibility not only through the improved flexibility of the PEF barrier layer itself, but also through the reduced material thickness of the cable and / or hose.

[0038] Of course, the PEF barrier layer can also have the same thickness as a PET barrier layer, resulting in a very dense and secure migration barrier.

[0039] The "layer thickness" is, in particular, the material thickness of the barrier layer in the radial direction.

[0040] In another embodiment, the barrier layer has a melting temperature of 235°C.

[0041] This allows the PEF barrier layer to be optimally applied by extrusion around an electrical conductor and / or under a sheath layer and permanently bonded to the sheath layer.

[0042] In a further aspect of the invention, the problem is solved by an electrical conductor for transmitting energy and / or information with a barrier layer, wherein the barrier layer comprises or consists of polyethylene furanoate and / or is a barrier layer as previously described, so that the electrical conductor is protected against migration of a substance and is flexible.

[0043] It is particularly advantageous that the electrical conductor is safely protected against the ingress of oxygen, water and / or humidity by the PEF barrier layer, without losing its bending flexibility.

[0044] In an additional aspect of the invention, the problem is solved by a cable for transmitting energy and / or information, wherein the cable has at least one electrical conductor, with a previously described barrier layer and / or an electrical conductor, such that the electrical conductor is protected against migration of a substance and the cable is flexible.

[0045] Thus, a cable remains flexible even if it has multiple conductors, each protected by its own barrier layer. Furthermore, the cable can have an additional barrier layer beneath the outer sheath, providing double redundancy for each conductor, thereby ensuring high operational reliability and a long service life for the cable.

[0046] A non-inventive aspect relates to a hose for conveying a substance with a barrier layer, wherein the barrier layer comprises or consists of polyethylene furanoate and / or is a previously described barrier layer, such that the hose is free from migration of the substance from its interior into an environment and is flexible.

[0047] This allows a medium and / or substance to be conveyed inside the hose without any substance escaping from the interior into the surrounding environment. A particular advantage is that the hose remains flexible despite the barrier layer, allowing even very long lengths of hose to be tightly coiled and stored.

[0048] In an additional aspect of the invention, the problem is solved by a method for manufacturing a coated cable using an extrusion device, comprising the following steps: - Inserting a continuous electrical conductor into the extrusion device and - Extruding a first molding compound to form a sheath layer and a second molding compound, wherein the second molding compound contains or consists of polyethylene furanoate, to form a barrier layer of the cable, wherein the extrusion of the first molding compound and the second molding compound is carried out in one operation, and - Applying the coated cable so that the coated cable has a barrier layer and is flexible.

[0049] This provides a process in which the barrier layer and the sheathing layer of a cable are manufactured in a single extrusion step.

[0050] To produce the barrier layer and the jacket layer in the same extrusion head (die head), extrusion is carried out at a temperature in the range of 210°C to 270°C, preferably from 230°C to 240°C.

[0051] It is particularly advantageous that, in the case of immiscible plastics, a form-fit is achieved through simultaneous extrusion, resulting in an adhesive bond that achieves sufficiently good adhesion between the plastic layers.

[0052] In addition to extrusion, fusion and thus a permanent bonding of an adjacent barrier layer and shell layer is also possible.

[0053] In another embodiment of the process, the barrier layer is produced as the inner layer and the shell layer as the outer layer during extrusion.

[0054] This allows for the production of either an outer cable sheath layer with a barrier layer directly underneath, or an outer hose sheath layer with a barrier layer directly underneath, or a cable sheath layer and, separately arranged, a barrier layer around the electrical conductor, or multiple barrier layers around multiple electrical conductors.

[0055] Consequently, the arrangement of the barrier layer or layers and the shell layer can be extruded according to the requirements of the manufactured product.

[0056] To increase the density and prevent the accumulation of unwanted substances between different layers, the barrier layer and the shell layer are permanently bonded by extrusion.

[0057] According to the invention, the extrusion of the first molding compound and the second molding compound takes place in one step.

[0058] This enables rapid extrusion into a coated cable and consequently fast, material- and energy-saving manufacturing.

[0059] In an additional aspect of the invention, the problem is solved by using polyethylene furanoate as a barrier layer around an electrical conductor and / or in a cable, so that the electrical conductor is protected against migration of a substance and is flexible and / or the cable is flexible and free from migration of the substance from its interior into an environment and is flexible.

[0060] The invention will now be explained in more detail using exemplary embodiments. These will show... Fig. 1 A schematic cross-sectional view of a signal line with a polyethylene furanoate layer and an electrical conductor, Fig. 2 a schematic sectional view of an electrical cable with sheathing and three strands with polyethylene furanoate layers and Fig. 3 a corrugated hose not according to the invention with a jacket layer and a polyethylene furanoate layer.

[0061] A signal line 121 contains an electrical conductor 105 made of copper with a diameter of 5 mm. The electrical conductor 105 is surrounded by a polyethylene furanoate layer 101 with a thickness of 20 µm. The polyethylene furanoate layer 101 is in turn directly surrounded by a sheathing layer 103 made of polypropylene with a thickness of 1.5 mm. The polyethylene furanoate layer 101 and the sheathing layer 103 were applied to the electrical conductor 105 by extrusion in the same extrusion head at 230°C and were thereby permanently fused together.

[0062] An electrical cable 123 has an outer sheath 103 and, inside, three strands 107, 109, and 111 surrounded by an inner material. The first strand 107, the second strand 109, and the third strand 111 each have a diameter of 2 mm and are each directly coated with a polyethylene furanoate layer 101. Each polyethylene furanoate layer 101 protects each of the three strands 107, 109, and 111 against the ingress of atmospheric moisture, which can migrate through the sheath 103 of the electrical cable 123 into its interior. Due to the flexible polyethylene furanoate layer 101 surrounding each of the three strands 107, 109, and 111, the electrical cable 123 remains flexible and can be stored and transported on a cable reel with an inner drum diameter of 50 mm.

[0063] A corrugated hose 125, not according to the invention, has a outer layer 103 made of polypropylene. A fusion-bonded polyethylene furanoate layer 101 is arranged beneath the outer layer 103. An inner cavity of the corrugated hose 125 is filled with hydraulic fluid 115.

[0064] The dense and closed polyethylene furanoate layer 101 prevents the migration of substances from the hydraulic fluid 115 through the polyethylene furanoate layer 101, thus preventing leakage into the environment of the corrugated hose 125.

[0065] The corrugated hose 125, which is not according to the invention, is manufactured in an extrusion device using the following work steps: Flowable polyethylene (PE) and flowable polyethylene furanoate are pressed through a die at a temperature of 235° C and a pressure of 300 bar, so that the corrugated hose 125 with the outer shell layer 103 made of polyethylene and the inner polyethylene furanoate layer 101 as a migration barrier is manufactured as a molded part.

[0066] By pressing the flowable polyethylene and the flowable polyethylene furanoate through the mold simultaneously in one step and lying molten next to each other, the polyethylene shell layer 103 and the polyethylene furanoate layer 101 are permanently bonded together.

[0067] The formed and coated hose is then discharged from the extrusion machine. The corrugated hose 125, manufactured according to the non-inventional method, has a nominal diameter of 25 mm and is wound onto a hose drum with an inner drum diameter of 200 mm. The manufactured corrugated hose 125 exhibits resistance to 100,000 bending cycles.

Claims

[1] Barrier layer (101) against migration of a substance, wherein the barrier layer (101) is arranged in a cable (121, 123) and / or around an electrical conductor (105, 107, 109, 111), and the barrier layer (101) comprises or consists of polyethylene furanoate, characterized by , that the barrier layer (101) is manufactured by extrusion together with a shell layer (103) in one operation, so that the barrier layer (101) is permanently bonded to the shell layer (103). [2] Barrier layer (101) according to claim 1, characterized by , that the barrier layer (101) has a layer thickness in a range of 0.01 mm to 10 mm. [3] Barrier layer according to one of claims 1 or 2, characterized by , that the barrier layer (101) has a layer thickness in the range of 0.05 mm to 1 mm. [4] Barrier layer (101) according to one of claims 1 to 3, characterized by, that the barrier layer (101) has a melting temperature of 235°C. [5] Electrical conductor (105, 107, 109, 111) for transmitting energy and / or information with a barrier layer (101), wherein the barrier layer (101) has polyethylene furanoate or consists of polyethylene furanoate, such that the electrical conductor (105, 107, 109, 111) is protected against migration of a substance and is flexible, characterized by , that the barrier layer (101) is manufactured by extrusion together with a shell layer (103) in one operation, so that the barrier layer (101) is permanently bonded to the shell layer (103). [6] Method for manufacturing a coated cable (121, 123) using an extrusion device, comprising the following steps: - Insertion of a continuous electrical conductor (105, 107, 109, 111) into the extrusion device and - Extruding a first molding compound to form a sheath layer (103) and a second molding compound, wherein the second molding compound comprises or consists of polyethylene furanoate, to form a barrier layer (101) of the cable (121, 123), wherein the extrusion of the first molding compound and the second molding compound is carried out in one operation, and - Applying the coated cable (121, 123) so that the coated cable (121, 123) has a barrier layer (101) and is flexible. [7] Method according to claim 6, characterized by that the extrusion takes place at a temperature in the range of 210°C to 270°C. [8] Method according to one of claims 6 or 7, characterized by , that during extrusion the barrier layer (101) is produced as the inner layer and the shell layer (103) as the outer layer.

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