METHOD FOR PRODUCING A TUBE OF THERMOPLASTIC RESIN HAVING POOR MELT FLOWABILITY AND APPARATUS THEREFOR

摘要

This invention provides a flexible tube of thermoplastic resin having poor melt flowability, the tube having an intrinsic viscosity of at least 3.5 dl/g, a tensile strength at break of 150 kg/cm<2>, a breaking time at hot internal pressure creep of at least 200 hours, an outer diameter of 50 mmo or less, and a ratio of the outer diameter to the wall thickness of 40 or less. This tube can be prepared from a thermoplastic resin having poor melt flowability by melting the thermoplastic resin having poor melt flowability in a screw extruder (1), and melt-extruding the molten thermoplastic resin from a tube die (7) having an L/D of at least 5 provided with a mandrel (5) rotatable with the rotation of the screw (3).