Apparatus for manufacturing a thermoplastic film

摘要

Extruded and blown tubular film(4) emerging from a die passes through a calibration and/or tube collapsing(3) equipment with film guides(5). A laminar air flow through each guide forms a laminar air cushion for contactless support of the tube. A microporous layer on the surface of each guide divides the air flow into partial streams with laminar flow though the individual pores towards the tube. Air pressure through the guides is at 0.4-4 bar, the air flow rate varying from 0.2l/min/sq dm at 0.5 bar to 1.6l/min/sq dm at 4 bar. The microporous layer(15) is 0.5-2.0mm thick and is produced by a powder mixture having components with different melting points. An independent claim is included for the process equipment whose film guides(5) at the calibrating and tube collapsing zones have a microporous layer on the surface facing the tube with a mean pore size of 5-100 microns.