Process for the manufacture of tubing based on cellulose hydrate having a coating on its inside and apparatus for carrying out the process

摘要

Disclosed is a process for coating the inside of a length of tubing comprising the steps of forming at least one 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 surface of the tubing above the level of the coating liquid with an initial layer of coating liquid; constricting the tubing adjacent to and above the level of the coating liquid with a metering device having a constriction zone which flattens a portion of the tubing passing therethrough to substantially eliminate all of the initial layer thereon and partially flattens the remaining portion of the tubing to allow a desired quantity of coating liquid to remain on 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 thereof and form an uninterrupted film. Also disclosed is an apparatus for carrying out the process.