Protective pipe jacket with a diffusion barrier

p0001The invention relates to a protective casing pipe with a diffusion barrier and a core tube of a plastic, and a protective jacket extruded.

p0002It is known that plastic pipes, for example, have made of polyethylene or other plastics with no precautions taken sufficient diffusion or Permeationsdichtigkeit regarding undesirable substances which might thereby enter the transported in plastic pipe medium or from this medium into the environment.

p0003To compensate for this unfavorable characteristic, are used in such plastic pipes diffusion barriers in the form of at least one additional layer of material surrounding the core tube completely.

p0004A particularly suitable material for a diffusion barrier to aluminum foil has been found. The aluminum foil is to helically wound slightly overlapping around the core tube. In this way a dense diffusion barrier is achieved over the entire length of pipe so that it remains tight, is wound when the plastic tube bent in the permissible range or for transport on a reel.

p0005A disadvantage is the relatively high consumption of aluminum foil, which must also have a minimum for safe handling thickness that is typically about 100 microns or even higher with such a diffusion barrier. Also, make sure that the bending radii are chosen to be sufficiently large to avoid exceeding the tensile strength and thus damage to the diffusion barrier in handling provided with such a diffusion barrier plastic pipes.

p0006Alternatively, the aluminum foil may also be placed along the pipe in order to shock, or such that a continuous, overlapping longitudinal seam is produced.

p0007Instead of aluminum foil also suitable extruded plastic layers have become known as diffusion barriers.

p0008Thus, in the <patcit id="pcit0001" dnum="DE4132984C1"><text>DE 41 32 984 C1</text></patcit> a plastic pipe comprising a core pipe with a protective jacket disposed thereon made of PVDF (polyvinylidene fluoride), wherein the core pipe and the protective casing are prepared by co-extruding. The protective jacket of PVDF has a high diffusion resistance to gases and liquids. The core tube is made of polyethylene, which has the advantage of high stress crack resistance and is resistant to aggressive media and soils, and is resistant to frost and microorganisms.

p0009The PVDF protective casing which has a thickness of 300 microns to 500 microns, can be additionally surrounded by a protective jacket made of polyethylene, which offers improved mechanical protection against damage. Finally, in addition to PVDF protective sheath, a protective layer may be provided in aluminum.

p0010The invention is based on the object to provide a protective casing pipe with a diffusion barrier and a core tube of a plastic, which can be produced particularly inexpensively with good diffusion density and wherein the diffusion barrier is a high variability in terms of adhesion to the core tube or the protective sheath , or it is also ensured to further surrounding the core tube layers.

p0011The object underlying the invention is achieved in a protective casing pipe with a diffusion barrier and a core tube of a plastic and an extruded protective sheath, characterized in that the diffusion barrier between the core pipe and the protective jacket diffusion hindering as multilayer film with at least one metal foil layer and / or at least one plastic film properties is embedded between different plastic layers.

p0012The use of such multilayer film has the advantage that the individual layers of plastic and the metal foil layer and the plastic film can be kept very thin, so that the multilayer film can be produced with little material cost.

p0013In a continuation of the invention, the individual layers of the multilayer laminated film of polyethylene, polypropylene, polyamide, or other suitable thermoplastics, as well as the metal foil layer and / or the plastic film and are preferably laminated with an adhesion promoter.

p0014With the models described below the invention will be depending on the orientation of the multilayer film different adhesion properties to the core pipe and the protective jacket reach.

p0015In a first variant of the invention, the multi-layer composite film has a layer sequence composed of a plastic layer of polyethylene, the metal foil layer and / or the plastic film and a plastic layer of a polypropylene copolymer.

p0016The different film structure, ie, the layer sequence of the multilayer film, the adhesion thereof can be the core tube, controlling the protective jacket or other layers of the plastic pipe.

p0017These properties of the multi-layer composite film can be used accordingly in the below described variations of the invention.

p0018In a second variant of the invention, the multi-layer composite film has a layer sequence comprising a layer of polyethylene, the metal foil layer and / or the plastic film and a layer of polypropylene.

p0019In a third variant of the invention, the multi-layer composite film has a layer sequence comprising a layer of polyethylene, the metal foil layer and / or the plastic film, a polyamide layer and a polypropylene layer.

p0020In a fourth variant of the invention, the multi-layer composite film has a layer sequence comprising a layer of polyethylene, the metal foil layer and / or the plastic film, a polyamide layer and a polypropylene copolymer layer.

p0021In a fifth variant of the invention, the multi-layer composite film has a layer sequence comprising a layer of polypropylene, the metal foil layer and / or the plastic film, a polyamide layer and a further layer of polypropylene.

p0022In a sixth variant of the invention, the multi-layer composite film has a layer sequence comprising a layer of a polypropylene, the metal foil layer and / or the plastic film, a polyamide layer and a polypropylene layer.

p0023In a seventh variant of the invention, the multi-layer composite film has a layer sequence composed of a polypropylene layer, the metal foil layer and / or the plastic film and a polyamide layer.

p0024The envisaged in the third to seventh variant of the invention the polyamide layer acts as an additional diffusion barrier and to increase the strength of the multilayer composite film.

p0025In a particular embodiment of the invention, the multilayer film is helically at the spiral longitudinal abutting edges overlapping, or to shock, wound around the core tube, the overlapping and spirally longitudinal abutting edges, or lying on Shock Shock edges additionally welded or glued can.

p0026In another particular embodiment, the multilayer film is longitudinally wrapped around the core tube such that protrude at the joint-free film webs, superimposed bottoms thereof into a film seam welded or glued.

p0027To achieve a particularly good seal, the film seam to a kind of labyrinth seal is one or multi seamed or is folded.

p0028The invention is explained in more detail using exemplary embodiments.

p0029The mantle tube according to the invention consists of a core pipe of a plastic, such as polyethylene (PE) as PE-100, PE-125, polypropylene (PP) or similar plastics, polybutene (PB), polyamide (PA), or else crosslinked or RC- materials, or even of filled plastics.

p0030The sheath may also be of a plastic, such as polyethylene (PE) as PE-100, PE-125, polypropylene (PP) or similar polymers, polybutene (PB), polyamide (PA), or else crosslinked or RC-materials consist ,

p0031The core pipe and the protective jacket may be made of the same or of different plastics. Also located between the core pipe and the protective casing a diffusion barrier.

p0032For the diffusion barrier is a multilayer film is used, wherein at least one metal foil layer is sandwiched between different plastic layers. As the metal foil layer preferably aluminum foil would be considered, although other suitable metals may be used to realize a diffusion barrier to special materials.

p0033Instead of the metal foil layer as a diffusion barrier can also be a plastic film made of a special plastic with diffusion-inhibiting properties, such as PVDF (polyvinylidene fluoride) or EVOH (ethylene-vinyl alcohol copolymer), a polyamide, other suitable plastic, or combinations of the metal foil layer and the plastic films, be used.

p0034The use of such multilayer film has the advantage that the individual layers of plastic and the metal foil layer or the plastic film can be kept particularly thin. This has the further advantage that the protective casing pipe is not stiffened by the unnecessary diffusion barrier, resulting in lower bending radii are allowed, without the risk that the multilayer film tears. Also the nominal diameter of the bonnet tube according to the invention is not greatly influenced by the multi-layer composite film.

p0035The individual layers of the multilayer composite film composed of polyethylene, polypropylene, polypropylene copolymer, polyamide, or other suitable thermoplastics and the metal foil layer and / or the plastic film in a different layer sequence. The individual layers are connected to each other, for example by adhesion promoters.

p0036The polypropylene used for the multilayer film may be polypropylene homopolymer (PP-H), a polypropylene Randomcopolymerisat (PP-R), or a polypropylene copolymer, for example, an isotactic polypropylene of classes.

p0037Depending on the arrangement of the multi-layer composite film, ie the order of the layers can be different adhesion properties to the core tube or to the protective sheath, or to other layers of the plastic pipe, reach.

p0038Subsequently, different variants of multi-layer composite film will be described.

p0039In a first variant, the multi-layer composite film has a layer sequence composed of a plastic layer of polyethylene, the metal foil layer and / or the plastic film and a plastic layer of a polypropylene copolymer.

p0040This can be depending on the orientation of the multilayer film different adhesion properties to the core pipe and the protective jacket reach.

p0041These particular properties of the multilayer composite film can be used accordingly in the below described variations of the invention.

p0042In a second variant, the multi-layer composite film has a layer sequence of Polethylen, the metal foil layer and / or the plastic film and a layer of polypropylene.

p0043In 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.

p0044In 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.

p0045In a fifth variant, the multi-layer composite film has a layer sequence comprising polypropylene, the metal foil layer and / or the plastic film, a polyamide layer and a layer of polypropylene.

p0046In a sixth variant, the multi-layer 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.

p0047In a seventh variant, the multi-layer composite film has a layer sequence composed of a polypropylene layer, the metal foil layer and / or the plastic film and a polyamide layer.

p0048Whereas the third intended to seventh variant polyamide layer acts as an additional diffusion barrier.

p0049The multilayer film may helically and are wound at the abutting edges overlapping about the core tube, the overlapping and spirally longitudinal abutting edges are either placed on each other, or welded or glued, to achieve a good seal. Alternatively, the multilayer film can be wrapped helically around the tube, wherein the spirally extending abutting edges are abutted and welded or glued.

p0050The multilayer composite film can also be longitudinally wrapped around the core tube such that it is overlapped at the joint.

p0051Alternatively, the multilayer film can be wrapped around the core tube and so along that protrude at the joint-free film webs. The free film webs are either simply overlaid, or with their superposed bottoms into a film seam welded or glued together.

p0052This film seam can be applied to the outside of the multilayer film, or to achieve a particularly good seal, be mono- or folded or folded several times into a kind of labyrinth seal.

p0053It is understood that the multi-layer composite film can also be built in a different sequence of layers corresponding to the respective application.