A method for coextruding a flow formed from sheet or tape of extrusible material a with a flow formed from sheet or tape of extrusible material b at a joint zone in a coextrusion die, and, an extruder comprising a coextrusion die for coextruding said flow rates. streams

摘要

"METHOD FOR COEXTRUSING AN EXTRUSIBLE MATERIAL SHEET OR RIBBON FLOW WITH AN EXTRUSIBLE MATERIAL B SHEET OR RIBBON IN A COEXTRUSION MATRIX, AND, EXTRUSOR MASSRIBUTE UNDERSTANDING A COTRUS MATERIAL THESE FLOWS ". A method and apparatus for coextruding two materials A and B, wherein B is extruded over A through an opening 3, wherein the separating wall between and streams A and B is formed with a reed latch 4 adapted to act as a check valve for flow from B to A, and additional devices are provided to extrude B in pulses through the opening. Pulses may be performed by opening and closing the latch by mechanical transmission device or by the effect of imposing pressure difference on the vane 4 by the flows of and / or B. The pulsating device preferably involves emboli 1. The invention is particularly suited for extruding a low viscosity material B over a higher viscosity material A, or for making sheets or tubes with alternating segments of differentiated flexibility, or for coextruding a stream or solid particles with a stream of liquid.