Patent ID: 7758796

Claim:
A process for forming an UHMWPE panel by ram extrusion, said panel having a width equal to or greater than 0.4 m, the process comprising: a) ram extruding UHMWPE through a slit die to provide a UHMWPE panel, the temperature of the panel exiting the slit die being below the crystalline melt temperature of the UHMWPE employed; b) restraining movement of the UHMWPE panel away from the die to create a back pressure between the die and a back pressure device, said back pressure device comprising a plurality of back pressure generating elements positioned across the width of the panel, the back pressure generated by at least one element being adjustable relative to the back pressure generated by at least one further element such that back pressure exerted on portions of the panel staggered across the width of the panel is differentially adjustable; c) establishing a restraining force between each back pressure generating element and the UHMWPE panel to provide stable extrusion conditions.