APPARATUS AND PROCESS FOR MAKING A CORRUGATION-FREE FOAM

摘要

An apparatus for extruding a polymeric foam from an extrudate comprising a polymeric resin and a blowing agent for providing an extrudate with a cellul ar structure upon extrusion, the apparatus comprising: an extruder having an inlet adapte d to receive the extrudate; an extrusion die comprising a substantially cylindrical body, an annular ridge extending from the cylindrical body and terminating in a peak, an annular slot located at the peak and defining an annular die opening forming an outlet fo r the extruder through which the extrudate is adapted to be pulled at a predetermined line speed, the extrusion die defining a longitudinal axis, and the annular die opening bein g concentrically oriented relative thereto and positioned therefrom at a first radial distanc e; a choke ring having an opening defined by an annular choke ring surface, the choke ring being positioned relative to the extruder such that the annular die opening is received within the choke ring opening, the choke ring opening being concentric about the longitudinal axis and positioned therefrom a second radial distance; and wherein the differenc e between the second radial distance and the first radial distance defines a gap between t he choke ring and the die opening and the gap is less than 4.57 mm.