Hydraulic pipe for transporting a cooling liquid

Abstract

A hydraulic pipe comprising an inner layer of polyphthalamide and an outer layer of thermoplastic material, the pipe having its thickness formed mainly by the thickness of the inner layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

The pipe in accordance with the invention comprises an inner layer made of polyphthalamide (PPA) having thickness lying in the range 1 mm to 1.5 mm.

The pipe also comprises an outer layer made of a fluoropolymer and preferably of a terpolymer of tetrafluoroethylene, hexafluoropropylene, and fluorinated vinylidene (THV). Other fluoropolymers can be used, such as: polyvinylidene fluoride (PVDF); ethylene tetrafluoroethylene (ETFE); ethylene fluoroethylene perfluoride (EFEP); polytetrafluoroethylene (PTFE); fluoroethylene propylene (FEP); perfluoroalkoxy (PFA); ethylene chlorotrifluoroethylene (ECTFE); . . . The outer layer has a thickness of about 0.2 mm.

The thickness of the pipe is formed mostly by the thickness of the layer of polyphthalamide.

The pipe in accordance with the invention is made by extrusion and the outer layer is in direct contact with the inner layer. This is made possible by the good properties of mutual adhesion between polyphthalamide and the fluoroterpolymer.

In a variant, when these adhesive properties are not sufficient given the conditions of use of the pipe, it is possible to add a bonding layer between the inner layer and the outer layer.

In another variant, it is possible to make the outer layer out of a thermoplastic elastomer (TPE) presenting properties similar to the fluoropolymer in terms of temperature and pressure, but being more flexible.

Naturally, the invention is not limited to the embodiment described and variant embodiments can be provided without going beyond the ambit of the invention as defined by the claims.

The pipe may have more than two layers and the order of the layers may be changed.

The materials used may include fillers or additives, e.g. to make them mutually compatible (improving their adhesion) or conductive, or providing mechanical reinforcement or color, . . . .

Claims

1. A hydraulic pipe comprising a layer comprising mostly polyphthalamide and at least one layer of another thermoplastic material, the pipe having thickness that is formed mainly by the thickness of the layer of polyphthalamide.

2. A pipe according to claim 1, in which the thickness of the layer of polyphthalamide is five to ten times greater than the thickness of the layer of thermoplastic material.

3. A pipe according to claim 2, in which the thickness of the layer of polyphthalamide is about 1 mm to 1.5 mm, and the thickness of the layer of thermoplastic material is about 0.2 mm.

4. A pipe according to claim 1, in which the outer layer of thermoplastic material is made of a thermoplastic elastomer.

5. A pipe according to claim 1, in which the outer layer of thermoplastic elastomer is made of a fluoropolymer.

6. A pipe according to claim 5, in which the fluoropolymer is a terpolymer of tetrafluoroethylene, hexafluoropropylene, and fluorinated vinylidene.

7. A pipe according to claim 1, in which the layer of thermoplastic material is directly in contact with the layer of polyphthalamide.

8. A pipe according to claim 2, in which the layer of polyphthalamide is the innermost layer of the tube.