Abstract: A fuel container with a wall of at least two wall shells which are separated at least partially from each other by an air gap between them. The dual shell wall structure helps to substantially improve the mechanical properties of the fuel container. Preferably, each wall shell consists of a plurality of layers of different polymeric or plastic materials. In a preferred embodiment of the invention a four layer co-extruded structure is provided; each shell comprises a layer of high density polyethylene (HDPE), a layer of filler material of treated, recycled plastics material referred to as “re-grind” and a vapor barrier layer of a plastic material substantially impermeable by hydrocarbons. The HDPE-layer may, be one surface layer of each wall shell and the vapor barrier layer is preferably the other surface layer of each wall shell. Depending on the material properties of the vapor barrier layer, an additional adhesive layer may also be necessary for connection with the adjacent layer.

Abstract: A method of forming multi-walled plastic containers in a single blow mold. In general, the method comprises disposing at least two separate parisons simultaneously into a blow mold and forming them to shape one after another by means of a special blow mandrel or pin. A substantially hollow, cylindrical first parison may be disposed around or outside of a substantially balloon or tube shaped second parison in an initially open blow mold. After closing the blow mold, the first or outer parison is expanded outwardly so that its outer surface engages the inner surface of the blow mold to assume the shape thereof, and thereafter, the second or inner parison is blown or outwardly expanded to an extent such that its outer surface at least partially engages the inner surface of the first or outer parison. The outer and inner parisons may be formed of different materials which may desirably impart different properties such as mechanical stability and resistance to permeation of fuel vapor from the container.

Abstract: An automotive plastic fuel tank with a wall having a structural layer of HDPE and a hydrocarbon fuel barrier layer of an EVOH based material with a binder layer between them. The barrier layer prevents the passage of hydrocarbons through the wall to the atmosphere. The barrier layer is on an exterior face of the wall and preferably on the interior of the tank in direct contact with fuel therein. Preferably, the barrier includes a layer of polyamide (A) or a mixture of polyamide (A) and polyolefin (B).

Abstract: An automotive plastic fuel tank with a wall having a structural layer of HDPE and a hydrocarbon fuel barrier layer of an EVOH based material with a binder layer between them. The barrier layer prevents the passage of hydrocarbons through the wall to the atmosphere. The barrier layer is on an exterior face of the wall and preferably on the interior of the tank in direct contact with fuel therein. Preferably, the barrier includes a layer of polyamide (A) or a mixture of polyamide (A) and polyolefin (B).