MXPA97002012A

MXPA97002012A - Pipe for transporting combusti

Info

Publication number: MXPA97002012A
Application number: MXPA/A/1997/002012A
Authority: MX
Inventors: Andre Maxime
Original assignee: Hutchinson
Priority date: 1995-07-20
Filing date: 1997-03-17
Publication date: 1998-04-01

Abstract

The invention relates to a pipe for transporting fuel, particularly for motor vehicles, which includes a thin layer (10) made of a thermoplastic such as a polyamide and having good fuel resistance properties, a protective layer (129 made from a crosslinkable thermoplastic, and optionally a film (14) disposed therebetween and made of a polymer that improves the adhesion between said layers and forms a barrier against the alcoholic

Description

PIPE FOR TRANSPORTING FUEL DESCRIPTION OF THE INVENTION The invention relates to a tube for transporting fuel, in particular in motor vehicles, but capable of being used also for transporting liquids or gases in industries, homes or food services, for example. Traditionally, tubes have been manufactured for the transportation of rubber fuel, although nowadays there is a tendency to replace them with tubes made of plastic material, which are less expensive, of lesser weight and less bulky, or of a composite structure, for example , comprising one or more layers of plastic material containing fluorine, and one or more rubber or elastomer protective layers (see, for example, patent publications: EPO 582 301, EPO 582 302, WO 93/21466 and WO 93 / 25835). However, the tubes of such composite structures usually have the drawback of being relatively thick due to the thickness of the rubber or elastomer protective layer and / or the high amount of layers constituting the tube. On the other hand, the regulations applicable to such pipes are becoming increasingly demanding, in particular with respect to the impermeability to fuels, and the known pipes are not always able to satisfy new standards, unless they use certain very impermeable materials but, at the same time, very expensive in terms of cost price and / or implementation cost. Accordingly, there is, at present, a need for a fuel transport tube which constitutes a significant improvement relative to known matter and which is capable of satisfying the following conditions: • low cost price; • little bulky; • good resistance to fire; • electrical conductor (to avoid electrostatic discharge that can result from accumulated electrostatic layers caused by friction between the fuel and the inner surface of the tube); • impermeable to fuel; • resistance to impacts at low temperatures; • resistance against physical-chemical attacks from external agents; and • compatible with conventional connection systems. The invention provides a tube that meets the preceding needs. In this way, the invention provides a tube for transporting fuel, in particular for a motor vehicle, the tube comprises a thin inner layer of thermoplastic material, which has good properties of impermeability and chemical resistance to fuel, and a protective layer that covers said fuel. inner layer, the tube is characterized in that the protective layer is made of a crosslinkable thermoplastic material.

The substance used to form the protective layer is conveniently made of PVC or polyethylene, which combines the advantages of a rubber or a vulcanizable elastomer, from the point of view of heat resistance, in particular, with the advantages of a thermoplastic material for manufacturing the tube, which can be manufactured by coextruding the thermoplastic material of the inner layer and the crosslinkable thermoplastic of the protective layer, or by extruding the thermoplastic of the inner layer and coating said inner layer with the crosslinkable thermoplastic of the layer protective (in particular by coextrusion or rope extrusion). Said tube has good characteristics of impermeability to fuels, by virtue of its inner layer selected from an appropriate thermoplastic material, and good resistance to fire thanks to the use of a thermoplastic material crosslinkable for said protective layer. The thickness of the inner layer of the thermoplastic material can be between 0.1 mm and 0.5 mm, the total thickness of the tube being between 1 mm and 3.5 mm. The material of the inner layer can be a polyamide, such as PA 11, PA 12, PA 6, or PA 66, or a polyester such as PET or PBT, or a fluorine-containing compound, such as PTFE, PFA, FEP, etc. Conveniently, the tube of the invention may further include an intermediate film of a polymer that improves adhesion between the inner layer and the protective layer, and that forms a barrier to alcohol. This characteristic is of considerable importance insofar as new fuels can present a non-negligible content of alcohols. The material of the intermediate film is selected from polyolefins (for example, polyethylene or polypropylene, etc.), optionally modified by maleic anhydride, EVOH (ethylene vinyl alcohol), EVA (ethylene vinyl acetate), polyurethanes, polyesters or any other material that promotes adhesion. According to another embodiment of the invention, the tube can also comprise a layer of vulcanizable elastomer or rubber that covers the above protective layer or is interposed between said inner layer and said protective layer. The rubber or the vulcanizable elastomer may be based on chlorosulfonated polyethylene (CSM), ECO, CR, N BR, H-N BR, X-N BR, POE or EPDM, for example. A film of an adhesive agent applied between the inner layer and the protective layer can be provided, said adhesive agent being selected, for example, from those commercially available under the THIXON and CHEMOSIL trademarks. The invention can be better understood and its other modalities, details and advantages are more evident from the following description given by way of example and with reference to the attached drawings in which: Figures 1, 2 and 3 are diagrammatic cross-sectional views of tubes of the invention. These tubes are intended, in particular, for use in motor vehicles, for example between the filling hole and the fuel tank, or between it and the engine. In the embodiment of Figure 1, the tube of the invention comprises an inner layer 10 of thermoplastic material, optionally a fluorine-containing material, which has good properties of impermeability to fuels, and a protective layer 12 which covers the inner layer and is made of a crosslinkable thermoplastic material. The material of the inner layer is conveniently a polyamide, for example such as PA 11, PA 12, PA 6 or PA 66, a polyester, for example such as PET (polyethylene terephthalate) or PBT (polybutylene terephthalate) or a fluorine-containing compound, for example PTFE (polytetrafluoroethylene), PFA (polyfluoroalkoxy-ethylene), PFE (hexafluoropolypropylene copolymer and tetrafluoroethylene copolymer), or the like, all thermoplastic polymer having good water impermeability being suitable. For a tube, whose internal diameter is approximately 8 mm, the thickness of the layer 10 can be between 0.1 mm and 0.5 mm. The crosslinkable thermoplastic material forming the protective layer 12 can be, for example, PVC or polyethylene. The total thickness of the layers 10 and 11 is about 1 mm, for example, for a tube whose internal diameter is 8 mm.

Conveniently, the film 14 between the layers 10 and 12 can be formed by a film of a polymer which improves the adhesion of the layers 10 and 12 and which also constitutes an alcohol barrier, which polymer can be a polyolefin such as polyethylene or polypropylene , for example, optionally modified with maleic anhydride, a polyurethane or even polyester, for example. The thickness of the film 14 can be very thin, for example from 0.05 mm to 0.1 mm. In the embodiment of Figure 2, the inner layer 10 and the layer 12 are the same as the embodiment of Figure 1, but the outer layer is coated within a layer 16 of vulcanizable elastomer, such as chlorosulfonated polyethylene (CSM), copolymer of aliglicidyl ether of epichlorohydrin-ethylene oxide (ECO), a chloroprene rubber (CR), a butadiene acrylonitrile rubber (N BR), a hydrogenated or halogenated N BR rubber (HN BR or XN BR), an elastomer of polyolefin (POE) or an EPDM. The thickness of layer 16 is less than or equal to 3 mm. Optionally, a film of an adhesive agent can be provided at the interface between layers 12 and 16, said adhesive agent being selected, for example, from those commercially available under the trade names of TH IXON AND CHEMOSIL. In the variant of the embodiment of Figure 3, the tube has an inner layer 10 of thermoplastic material similar to the embodiments of Figures 1 and 2, an intermediate layer 16 of rubber or vulcanizable elastomer coating the inner layer 10 and a outer layer 12 of crosslinkable thermoplastic, the substances constituting layers 12 and 16 being similar to those of the embodiment of Figure 2. A film of adhesive agent 18 can be provided as described above, between layers 12 and 16, as thus also between layers 10 and 16. With respect to the embodiment of Figure 1, there can be a film of a polymer to form an anti-alcohol barrier between layers 10 and 12 (Figure 2) or between layers 10 and 16. (Figure 3). The tubes of the invention have very good characteristics of fuel impermeability, flexibility and flame resistance; their cost price is moderate, they are compact (good adhesion between the various layers makes it possible to obtain a uniform behavior structure when folded, without delamination) and their resistance to impacts and external attacks is entirely satisfactory. To avoid the risk of external discharge, the inner layer can be made to be slightly electrically conductive, incorporating electroconductive agents in the thermoplastic, for example, carbon black or powdered metals. The modalities shown and described above are only illustrative, to enable one skilled in the art to make and use the invention. Undoubtedly, modifications can be made in the construction, materials, arrangement and application, without departing from the spirit and scope of the invention.

Claims

1 .- A tube for transporting fuel, in particular for automotive vehicles, comprising a thin inner layer of thermoplastic material, which has good properties of impermeability to fuel, and a protective layer covering the inner layer, characterized in that said protective layer It comprises a crosslinkable thermoplastic material.

2. A tube according to claim 1, wherein the total thickness is in the range of 1 mm to

3.5 mm, the inner layer of thermoplastic material having a thickness between 0.1 mm and 0.5 mm. 3. - A tube according to claim 1 or 2, wherein said crosslinkable thermoplastic material is PVC or polyethylene.

4. A tube according to any of the preceding claims, wherein the inner layer is made of polyamide, such as PA 1 1, PA 12, PA 6 or PA 66, or polyester, such as PET or PBT or a fluorine-containing compound, such as PTFE, PFA or FEP.

5. A tube according to any of the preceding claims, wherein includes an intermediate film of a polymer that improves the adhesion between the inner layer and the protective layer and that forms a barrier against alcohol.

6. A tube according to claim 5, wherein the material of the intermediate film is selected from polyolefins such as polyethylene or polypropylene, such as modified by maleic anhydride, EVOH, EVA, polyurethanes or polyesters.

7. A tube according to any of the preceding claims, wherein it includes a layer of vulcanizable elastomer or rubber that covers the protective layer or is interposed between the inner layer and the protective layer.

8. A tube according to claim 7, wherein the vulcanizable elastomer is selected from the group consisting of CMS, ECO, CR, N BR, H N BR, XN BR, POE, or EPDM.

9. A tube according to claim 7 or 8, wherein the thickness of the vulcanizable elastomer layer is less than or equal to 3 mm.

10. A tube according to any of the preceding claims, wherein it includes a film of an adhesive agent applied between said inner layer and said protective layer, said adhesive agent being selected from, for example, those commercially available under the trade names. by TH IXON AND CH EMOSI L.