Production of UHMWPE sheet materials
AssigneeQuadrant Epp AG
InventorsJoseph V. Gregg, Wesley Allen Kohler, Lyle D. Berning
Life of this patent
Estimating the term…
Abstract
UHMWPE panels of large width may be prepared by a continuous ram extrusion process by employing a slit die which preferably narrows from both sides in a direction transverse to the machine direction, and/or which employs a plurality of transversely positioned cooling zones located on the top and the bottom of the die, proximate the exit thereof. The panel exits the die at a temperature lower than the crystalline melt temperature.
Claims22
A ram extrusion process for preparing UHMWPE panels of widths greater than 0.6 m as extruded, comprising:
- providing a slit die having a width of greater than 0.6 m which has a substantially rectangular cross-section under ram extrusion operating pressure, the die having a top portion and a bottom portion and an inlet face and an exit face, and having at least three independently controllable cooling zones in each of the top portion and bottom portion, said cooling zones located proximate the exit face of the die, and positioned along the width of the die, such that the temperature of each respective cooling zone may be adjusted to vary the temperature of respective portions of the die transverse to the exit face;
- incrementally introducing UHMWPE resin particles into the die under pressure from a ram;
- heating the UHMWPE particles to a temperature above the crystalline melt temperature of UHMWPE to form a substantially continuous molten thermoplastic;
- cooling the UHMWPE to a temperature below the crystalline melt temperature while within the die and while maintaining contact with the walls of the die;
- and
- obtaining a solidified UHMWPE panel product which has exited the die.
A process for producing an UHMWPE panel of greater than 0.6 m width, comprising ram extruding UHMWPE through a slit die contained within a support structure, the exit slit of the slit die not having a substantially rectangular shape as manufactured, but the die coacting with the support structure to distort to a substantially rectangular shape under ram extrusion pressure.
A process for extruding UHMWPE panels of greater than 0.4 m width, comprising ram extruding UHMWPE through a slit die at a temperature higher than the crystalline melt temperature of the UHMWPE and cooling the UHMWPE to a temperature below the crystalline melt temperature while still within the slit die, said cooling effected by a plurality of independently controllable cooling zones located above and below the slit proximate an exit face of the slit die, and the respective plurality of independently controllable cooling zones positioned across the width of the die.
Dependencies are inferred from the claim text.