Protective pipe jacket with a diffusion barrier

0001The invention relates to a protective jacket pipe with a diffusion barrier and a core pipe made of a plastic, as well as a protective jacket extruded on.

0002It is known that plastic pipes, for example made of polyethylene or other plastics, do not have sufficient diffusion or permeation tightness with regard to undesired substances without special protective measures, which could get into the medium transported in the plastic pipe or out of this medium into the environment.

0003In order to compensate for this unfavorable property, diffusion barriers in the form of at least one additional layer of material that completely surrounds the core tube are used in such plastic tubes.

0004Aluminum foil has proven to be a particularly suitable material for a diffusion barrier. The aluminum foil is wrapped helically around the core tube with a slight overlap. In this way, a tight diffusion barrier is achieved over the entire length of the pipe, which remains tight even if the plastic pipe is bent within the permissible range or wound onto a reel for transport.

0005A disadvantage of such a diffusion barrier is the comparatively high consumption of aluminum foil, which must also have a minimum thickness for safe handling, which is usually around 100 μm or more. When handling plastic pipes provided with such a diffusion barrier, care must also be taken to ensure that the bending radii are sufficiently large in order to avoid exceeding the tensile strength and thus damaging the diffusion barrier.

0006Alternatively, the aluminum foil can also be laid lengthwise around the pipe butt-joined, or in such a way that a continuous, overlapping longitudinal seam is created.

0007Instead of aluminum foil, suitable extruded plastic layers have also become known as diffusion barriers.

0008So will in the<patcit id="pcit0001" dnum="DE4132984C1"><text>DE 41 32 984 C1</text></patcit> describes a plastic tube consisting of a core tube with a protective jacket made of PVDF (polyvinylidene fluoride) arranged thereon, the core tube and the protective jacket being produced by coextrusion. The protective coating made of PVDF has a high level of imperviousness to gases and liquids. The core tube is made of polyethylene, which has the advantage of high resistance to stress cracking and is resistant to aggressive media and soil, as well as being insensitive to frost and microorganisms.

0009The PVDF protective jacket, which has a thickness of 300 to 500 µm, can also be surrounded by a protective jacket made of polyethylene, which offers improved mechanical protection against damage. Finally, a protective layer made of aluminum can be provided in addition to the PVDF protective jacket.

0010Furthermore goes from the<patcit id="pcit0002" dnum="WO2004094887A1"><text>WO 2004/094887 A1</text></patcit> a plastic/metal composite pipe, in particular a composite pipe with an aluminum jacket, for use as an oxygen-impermeable heating pipe. There is an oxygen diffusion barrier (e.g. made of EVOH) on a plastic base tube, above which there is an adhesion promoter layer and a non-overlapping metal strip placed on top as reinforcement. An outer jacket can be applied over the metal strip by means of a further adhesive layer, with adhesive layers being located between all of the layers.

0011The metal strip used here has no diffusion layer barrier function.

0012In the<patcit id="pcit0003" dnum="DE202007008875U1"><text>DE 20 2007 008875 U1</text></patcit> describes a multilayer fluid line for heating purposes with a base layer and a diffusion barrier layer surrounding it, which contains at least one copper layer with a thickness of 10-50 μm and a base layer made of a crosslinked polyethylene, polyethylene 100 or polybutene.

0013There are adhesion promoter layers between all layers.

0014In<nplcit id="ncit0001" npl-type="b"><text>DATABASE WPI, Week 201378, Thomson Scientific, London, UK; AN 2013-G69775 XP002732923</text></nplcit>, -&amp; <patcit id="pcit0004" dnum="CN102825875A"><text>CN 102 825 875 A</text></patcit>, a multilayer barrier film is described that includes a first barrier layer of EVOH (as an oxygen barrier), a second crystalline and/or non-crystalline polyamide layer, and a third layer of EVOH or polyamide.

0015The inner and outer films are multilayer and are polyethylene based layers sandwiched by an adhesion promoter consisting of a polymerised anhydride polymer, a transparent LDPE or a linear LDPE. The individual layers are produced individually and cured at 20 - 30 °C for 8 - 72 hours. This multilayer film is suitable as the outer layer of flexible pipes.

0016In the<patcit id="pcit0005" dnum="EP0617219A2"><text>EP 0 617 219 A2</text></patcit> the use of barrier-layer plastics as reinforcements in motor vehicle pipelines in the form of laminate composite wholes is described. Possible barrier layer plastics are: EVOH, PE, PP, PMP, POM, PBT, PVDF, FEP, ETFE, ECTFE, TFA or compatible mixtures. The composite laminate assemblies are created by adhesion promoter films.

0017The<patcit id="pcit0006" dnum="EP1162061A1"><text>EP 1 162 061 A1</text></patcit> refers to thermoplastic multilayer composites for a multilayer fuel line in the form of a multilayer hose or pipe with a barrier effect using adhesion promoters. Polyamides are particularly suitable for the multi-layer composites.

0018In the<patcit id="pcit0007" dnum="EP0428833A2"><text>EP 0 428 833 A2</text></patcit> describes a motor vehicle pipeline made of polyamides by coextrusion. The pipe consists of an outer layer made of polyamide, an intermediate layer made of a copolymer of ethylene or vinyl alcohol and an inner layer made of polyamide, with the intermediate layer being interposed with an adhesion promoter layer.

0019The<patcit id="pcit0008" dnum="CN102825875A"><text>CN102825875A</text></patcit> deals with a multilayer film composed of an outer film, a multilayer barrier film and an inner film suitable for packaging materials and soft composite hoses. The individual layers of the multilayer barrier film consist of ethylene vinyl alcohol (EVOH) as the first layer, crystalline or non-crystalline polyamide (preferably nylon) as the second layer, and EVOH or polyamide as the third layer. The outer and inner multi-layer films, as well as the barrier films, are manufactured independently and post-treated at low temperatures. There is no reference to protective jacket pipes.

0020Furthermore, in the<patcit id="pcit0009" dnum="DE112007000275T5"><text>DE 11 2007 000 275 T5</text></patcit> describes a tape-covered multi-layer tube and a method for its manufacture, which is essentially hermetically sealed. The multi-layer pipe consists of an inner pipe, a diffusion barrier (multi-layer tape laminate with diffusion barrier material), thermoplastic film layers and an adhesive layer between the diffusion barrier and a thermoelastic film layer. A silicone tube can also be used as the inner tube so that it can slide within the diffusion barrier tape laminate.

0021The invention is now based on the object of creating a protective jacket pipe with a diffusion barrier against unwanted substances and a core tube made of a plastic, which can be produced particularly inexpensively with good diffusion tightness and where the diffusion barrier allows a high degree of variability in terms of adhesion to the core tube or .At the protective jacket, or also to other layers surrounding the core tube.

0022The object on which the invention is based is a protective jacket pipe with a diffusion barrier and a core pipe made of a plastic such as polyethylene, polypropylene or similar plastics, namely polybutene, polyamide, or crosslinked or RC materials, or filled plastics, and a diffusion barrier extruded protective jacket made of polyethylene, polypropylene or similar plastics such as polybutylene, polyamide, or cross-linked or RC materials, solved by that<ul id="ul0001" list-style="none" compact="compact"><li>the diffusion barrier between the core tube and the protective jacket is designed as a multi-layer composite film,</li><li>which has at least one metal foil layer and/or at least one plastic foil with diffusion-inhibiting properties, which is arranged between different plastic layers with the following layer sequences:<ul id="ul0002" list-style="none"><li>a layer of polyethylene or polypropylene and</li><li>layers of polypropylene, polypropylene copolymer or polyamide, or polyamide and polypropylene copolymer, or polypropylene,</li><li>wherein the individual layers of the multilayer composite film are laminated with an adhesion promoter.</li></ul></li></ul>

0023The use of such a multi-layer composite film has the advantage that the individual plastic layers and the metal foil layer or the plastic film can be kept particularly thin, so that the multi-layer composite film can be produced cost-effectively using little material.

0024With the variants of the invention described below, different adhesion properties to the core tube or to the protective jacket can be achieved depending on the orientation of the multilayer composite film.

0025In a first variant of the invention, the multilayer composite film has a layer sequence made of a plastic layer made of polyethylene, the metal foil layer and/or the plastic film and a plastic layer made of a polypropylene copolymer.

0026The adhesion to the core pipe, the protective jacket or other layers of the plastic pipe can be controlled by the different film structure, ie the layer sequence of the multi-layer composite film.

0027These properties of the multilayer composite film can also be used accordingly in the variants of the invention described below.

0028In a second variant of the invention, the multi-layer composite film has a layer sequence consisting of a layer made of polyethylene, the metal foil layer and/or the plastic film and a layer made of polypropylene.

0029In a third variant of the invention, the multi-layer composite film has a layer sequence consisting of a layer made of polyethylene, the metal foil layer and/or the plastic film, a polyamide layer and a polypropylene layer.

0030In a fourth variant of the invention, the multi-layer composite film has a layer sequence consisting of a layer made of polyethylene, the metal foil layer and/or the plastic film, a polyamide layer and a polypropylene copolymer layer.

0031In a fifth variant of the invention, the multi-layer composite film has a layer sequence consisting of a layer made of polypropylene, the metal foil layer and/or the plastic film, a polyamide layer and a further layer made of polypropylene.

0032In a sixth variant of the invention, the multi-layer composite film has a layer sequence made up of a polypropylene layer, the metal foil layer and/or the plastic film and a polyamide layer.

0033The polyamide layer provided in the third to sixth variants of the invention serves as an additional diffusion barrier and to increase the strength of the multilayer composite film.

0034In a particular embodiment of the invention, the multi-layer composite film is wound helically around the core tube, overlapping at the spiral longitudinal abutting edges, or in abutment, with the overlapping and spiral longitudinal abutting edges or the abutting abutting edges additionally being welded or glued to one another can.

0035In a further special embodiment of the invention, the multi-layer composite film is laid lengthwise around the core tube in such a way that free film webs protrude at the joint, the undersides of which are welded or glued together to form a film seam.

0036In order to achieve a particularly good seal, the film seam is folded or turned over once or several times to form a type of labyrinth seal.

0037The invention is explained in more detail below using exemplary embodiments.

0038The protective jacket pipe according to the invention consists of a core pipe made of a plastic such as polyethylene (PE), such as PE-100, PE-125, polypropylene (PP) or similar plastics, polybutene (PB), polyamide (PA), or cross-linked or RC Materials, or also from filled plastics.

0039The protective sheath can also be made of a plastic such as polyethylene (PE), such as PE-100, PE-125, polypropylene (PP) or similar plastics, polybutene (PB), polyamide (PA), or cross-linked or RC materials .

0040The core tube and the protective jacket can be made of the same or different plastics. Furthermore, there is a diffusion barrier between the core tube and the protective jacket.

0041A multi-layer composite film is used for the diffusion barrier, in which at least one metal foil layer is embedded between different plastic layers. Aluminum foil is preferably used as the metal foil layer, although other suitable metals can also be used in order to implement a diffusion barrier against special materials.

0042Instead of the metal foil layer as a diffusion barrier, a plastic foil made of a special plastic with diffusion-inhibiting properties, such as PVDF (polyvinylidene fluoride) or EVOH (ethylene-vinyl alcohol copolymer), a polyamide, another suitable plastic, or combinations of the metal foil layer and the plastic foils, be used.

0043The use of such a multi-layer composite film has the advantage that the individual plastic layers and the metal foil layer or the plastic film can be kept particularly thin. This has the further advantage that the protective jacket pipe is not unnecessarily stiffened by the diffusion barrier, which allows smaller bending radii without the risk of the multi-layer composite film tearing. The nominal diameter of the protective jacket pipe according to the invention is also only insignificantly influenced by the multi-layer composite film.

0044The individual layers of the multi-layer composite film consist of polyethylene, polypropylene, polypropylene copolymer, polyamide or other suitable thermoplastics and the metal foil layer and/or the plastic film in different layer sequences. The individual layers are connected to one another, for example by means of adhesion promoters.

0045The polypropylene used for the multilayer composite film can be, for example, an isotactic polypropylene of the classes polypropylene homopolymer (PP-H), a polypropylene random copolymer (PP-R), or else a polypropylene copolymer.

0046Depending on the arrangement of the multi-layer composite film, ie the order of the layers, different adhesion properties to the core pipe or to the protective jacket, or also to other layers of the plastic pipe, can be achieved.

0047Different variants of the multilayer composite film are described below.

0048In a first variant, the multilayer composite film has a layer sequence made of a plastic layer made of polyethylene, the metal foil layer and/or the plastic film and a plastic layer made of a polypropylene copolymer.

0049Depending on the orientation of the multi-layer composite film, different adhesion properties to the core tube or to the protective jacket can thus be achieved.

0050These special properties of the multilayer composite film can also be used accordingly in the variants of the invention described below.

0051In a second variant, the multi-layer composite film has a layer sequence made of polyethylene, the metal foil layer and/or the plastic film and a layer made of polypropylene.

0052In a third variant, the multi-layer composite film has a layer sequence made of polyethylene, the metal foil layer and/or the plastic film, a polyamide layer and a polypropylene layer.

0053In a fourth variant, the multi-layer composite film has a layer sequence made of polyethylene, the metal foil layer and/or the plastic film, a polyamide layer and a polypropylene copolymer layer.

0054In a fifth variant, the multilayer composite film has a layer sequence made of polypropylene, the metal foil layer and/or the plastic film, a polyamide layer and a layer made of polypropylene.

0055In a sixth variant, the multilayer composite film has a layer sequence made of a polypropylene, the metal foil layer and/or the plastic film, a polyamide layer and a polypropylene layer.

0056In a seventh variant, the multi-layer composite film has a layer sequence made up of a polypropylene layer, the metal foil layer and/or the plastic film and a polyamide layer.

0057The polyamide layer provided in the third to seventh variants serves as an additional diffusion barrier.

0058The multi-layer composite film can be wrapped helically and overlapping at the butt edges around the core tube, with the overlapping and spirally longitudinal butt edges either being placed one on top of the other or being welded or glued to one another in order to achieve a good seal. Alternatively, the multi-layer composite film can also be wound helically around the core tube, with the helically running abutting edges butting and being welded or glued to one another.

0059The multi-layer composite film can also be placed lengthwise around the core tube in such a way that it overlaps at the joint.

0060Alternatively, the multi-layer composite film can also be laid lengthwise around the core tube in such a way that free film webs protrude at the joint. The free film webs are either simply laid one on top of the other, or welded or glued together with their undersides lying on top of one another to form a film seam.

0061This film seam can be applied to the outside of the multi-layer composite film, or in order to achieve a particularly good seal, it can be folded or folded over once or several times to form a type of labyrinth seal.

0062It goes without saying that the multi-layer composite film can also be built up in a different sequence of layers according to the respective application.