Elongated fuel and vapor tube having multiple layers and method of making the same

DETAILED DESCRIPTION The present invention is an elongated tube for connection to a motor vehicle system to transport fluids containing hydrocarbons from point to point.
Such elongated tubes could be employed as part of a fuel line, a vapor return line or a vapor recovery line.
The elongated tube of the present invention includes a first layer disposed radially innermost and having an inner surface capable of prolonged exposure to fluids containing hydrocarbons and an outer surface spaced a predetermined radial thickness from the inner surface.
The first layer is composed of a fluoroplastic material having a melt temperature between about 160.
degree.
and about 200.
degree.
C.
and a specific gravity between about 1.
95 and about 1.
98.
The preferred fluoroplastic material is a terpolymeric material containing tetrafluoroethylene, vinylidine difluoride and hexafluoropropylene.
A second layer has a second predetermined radial thickness greater than the thickness of the first layer.
The second layer has an inner face capable of sufficiently laminar adhesion to the first layer and an outer surface opposed thereto.
The second layer consists essentially of an extrudable, melt-processible thermoplastic material.
The outer surface of the second layer preferably is directly contactable with the surrounding environment external to the tubing of the present invention.
In a first embodiment of the present invention, the first layer is an essentially unitary layer.
In the second embodiment, the first layer is made up of two sublayers; the radially innermost sublayer composed of a fluoroplastic material having a melt temperature between about 160.
degree.
and 200.
degree.
C.
and a specific gravity between about 1.
95 and about 1.
98.
The preferred fluoroplastic material is a terpolymeric material containing tetrafluoroethylene, vinylidine difluoride and hexafluoropropylene.
In this second embodiment, the innermost sublayer is capable of dissipating electrostatic energy in a range between about 10.
sup.
4 to 10