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Abstract

An apparatus for the extrusion a multi-layer parison comprises an extrusion blow molding head having a bore passing through the head with a diverter sleeve located within the bore. There is a first manifold in fluid communication with a first die inlet, the first manifold substantially surrounds the diverter sleeve and is in fluid communication with a proximal end of a flow path formed by the diverter sleeve and the bore; wherein the flow path extends from the proximal end to a head exit and a first land that has a variable width is positioned between the first manifold and the flow path. A second manifold is in fluid communication with a second die inlet, the second manifold substantially surrounds the diverter sleeve and is in fluid communication with the flow path at a first location downstream from the proximal end of the flow path; wherein the flow path has a width that increases at the first location; and a second land that has a variable width positioned between the second manifold and the flow path. The first manifold, the first land, the second manifold, and the second land are sized so that the flow of material through the flow path from proximal end to the head exit is substantially consistent to create a multi-layer flow of material to form the parison having a wall of a substantially similar cross section. The method includes introducing predefined volumes of polymer melt to the manifolds, passing the volume to the flow path and extruding the parison.

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