Process for production of multi-layer pipes for draw-forming

Abstract

A process for the production of a multi-layer pipe to be used for formation of a bottle by drawblow-forming, comprising forming by co-extrusion a pipe having inner and outer layers of a polyester composed mainly of ethylene terephthalate units and an intermediate layer of an oxygen-barrier resin interposed between the inner and outer layers. An adhesive resin layer is preferable interposed between every two adjacent layers. The co-extruded multi-layer pipe is sized in the molten state so that the diameter of the pipe is uniform. The process continues by cooling the outer portion of the molten multi-layer pipe by contact with water and simultaneously introducing an inert gas or an inert gas containing a water mist into the interior of the pipe to thereby cool the inner portion of the pipe and prevent oxidation in the pipe. A multi-layer pipe prepared according to this process is excellent in the transparency and the draw-formability into a multi-layer drawn bottle.