Process for the manufacture of tubular packaging sheaths having a coating on the inside, and apparatus for carrying out the process

Abstract

Disclosed is a process for forming an uninterrupted coating of uniform thickness on the inside of a length of tubing which comprises the steps of forming a loop of tubing with a downwardly inclined portion and an upwardly inclined portion; filling the cavity of the tubing forming the loop with a coating liquid; transporting the tubing along its longitudinal axis in a substantially vertically upward direction to coat the inside of the tubing, above the level of the coating liquid, with an initial layer of coating material; constricting the tubing to lay partially flat along a narrow zone running transverse to the direction of transportation above the level of the coating liquid to retain the greater part of the coating liquid in the constriction zone and form a thin layer of coating liquid of desired thickness on the inside; of the tubing issuing from the constriction zone; filling the cavity of the tubing issuing from the constriction zone with support gas; and exposing the tubing to the action of heat at a sufficiently high temperature to fuse the coating layer to the inside of the tubing and form an uninterrupted film of uniform thickness on the inside of the tubing. Also disclosed is an apparatus for carrying out the process of the present invention.

Dependencies are inferred from the claim text.