heating oven is maintained at a temperature of 230 u00b0 c under these conditions all the polypropylene melts and is entirely distributed throughout the braid interstices and onto the surface of the braid no solid polypropylene core residue remains as the braid emerges from spinneret i large quantities of excess polypropylene which has melted out and formed nubs on the surface is trimmed off by a smoothing die 12 having an internal diameter id of 0 180 mounted at the outlet of spinneret i the braid then continues through a guide 15 to spinneret ii designated 39 which is an extrusion coating die apparatus shown in detail in fig2 the smoothed precoated braid is pulled through spinneret ii by a roll godet 50 tension is let down on roll 50 so that some overfeed i e a stretch ratio sr of approximately 0 9 is applied isotactic polypropylene chips are melted in heated reservoir 41 maintained at a temperature of 260 u00b0 c and the melt is forced by means of extruding weights 43 applying a force of 0 233 kg to a piston 45 into and through the tubing type extrusion coating die apparatus 39 directing particular attention to fig2 the extruding coating apparatus 39 is comprised of a holder indicated.