DE29706045U1 - Multi-layer plastic pipe - Google Patents

Description

B/33.815/70-R1

Unicor Rohrsvsteme GmbH, Industriestraße 56, 97437 Haßfurt

Multilayer plastic pipe

The invention relates to a multilayered plastic pipe with an inner layer made of new material with a smooth inner pipe surface and with a layer with a corrugated outer surface, wherein the corrugated layer with a ribbed longitudinal profile consists of a recycled material that is foamed by a blowing agent.

Such a multilayer pipe or a method for producing such a pipe is known from DE 43 25 021 Cl.

A multi-layer plastic pipe with a smooth inner pipe and a corrugated outer pipe connected to it is known, for example, from DE 296 16 289 Ul of the applicant. In this known multi-layer plastic pipe, the smooth inner pipe consists of a first plastic and the corrugated outer pipe consists of a second plastic that foams up using a blowing agent, whereby the wall thickness of the corrugated outer pipe is at least 10% of the average corrugation width of the

corrugated outer pipe. The inner pipe can be made of pure plastic or recycled material.

DE-AS 17 04 718 discloses a double-walled plastic pipe with an annular or helical grooved outer layer and a smooth inner layer, which are produced by two annular nozzles fed from two separate, independently controllable extruders.

DE-OS 2 316 835 discloses a method for the continuous production of plastic hollow profiles from two or more layers, wherein at least one layer of the hollow profile consisting of two or more layers consists of a foamed plastic material.

All of these known multilayer pipes have a smooth inner pipe surface and a corrugated outer surface. This also applies to the multilayer plastic pipe known from DE 41 28 654 Al, which is intended in particular for waste water or cables, whereby recycled materials can also be used. In order to achieve the required strength properties with reduced weight, an intermediate pipe is provided between the smooth inner pipe and the corrugated or compact outer pipe in this known multilayer pipe, which has a different structure to the outer pipe.

DE-OS 2 042 031 describes a process for producing corrugated pipes from thermoplastics, whereby a tube is first continuously formed from the thermoplastics using an extrusion press, which is then profiled by internal pressure with the help of a moving forming chain into a corrugated pipe with wave crests and wave troughs and then cooled. Concentrically to the profiled corrugated pipe,

at least one second hose made of thermoplastic is extruded. This second hose made of thermoplastic is connected or welded on the inside or outside as a smooth jacket at least to the corrugation peaks of the corrugated pipe. The smooth jacket can consist of a plastic foam material that can also be pressed into the corrugation troughs between adjacent corrugation peaks.

From DE 44 30 038 A1 a multilayered pipe made of plastic with an inner and an outer layer is known, wherein the inner layer has a smooth inner surface and a ribbed outer surface and the outer layer is formed by a smooth outer pipe.

The invention is based on the object of developing a multilayer pipe of the type mentioned at the outset in such a way that its application properties are further improved by a smooth outer surface.

This object is achieved according to the invention in a multilayer pipe of the type mentioned at the beginning in that a smooth outer pipe is connected to the layer made of a recycled material with a corrugated outer surface. In the pipe according to the invention, the said corrugated layer can consist of a mixture of common polyolefins without PVC. The inner layer and/or the outer layer, i.e. the smooth outer pipe, preferably consist of a single-grade plastic. This can be PE or PP. Accordingly, the corrugated layer between the inner and outer layers can consist of PE or PP recycled material.

An embodiment of the multilayer pipe according to the invention is shown in the drawing, sectioned lengthwise on one side. The figure shows, not to scale, a design of the multilayer pipe with an inner layer 12, an outer layer 14 and a layer 16 provided between the inner layer 12 and the outer layer 14. The inner layer 12 and the outer layer 14 are each formed by smooth pipes made of pure plastic material. The layer located between the inner and outer layers 12 and 14 has a smooth inner surface 18 and a corrugated outer surface 20. The layer 16 is connected or welded over a large area with its inner surface 18 to the smooth inner layer 12. The corrugated outer surface 20 of the layer 16 is only connected or welded to the smooth outer layer 14 or the smooth outer pipe along the corresponding wave crest sections 22. The connection of inner layer 12, outer layer 14 and intermediate layer 16 is achieved by known coextrusion.

Claims (3)

B/33.815/70-R1 Unicor Rohrsvsteme GmbH. Industriestraße 56. 97437 Haßfurt Claims; 1. Multi-layered plastic pipe with an inner layer (12) made of new material with a smooth inner pipe surface, and with a layer (16) with a corrugated outer surface (20), the corrugated layer (16) consisting of a recycled material which is foamed by a blowing agent, characterized in that a smooth outer tube (14) is connected to the layer (16) having a corrugated outer surface (20). 2. Pipe according to claim 1, characterized in that the corrugated intermediate layer (16) consists of a mixture of common polyolefins without PVC. 3. Pipe according to claim 1, characterized in that the inner layer (12) and/or the outer layer (14) consists of pure plastic. . Pipe according to claim 3, characterized in that the pure plastic is made of PE or PP.