Coating of plastics materials.

摘要

A method of and apparatus forming an enveloping coating on a web of plastics material, in particular a flattened tube of weldable plastics material having had welded thereto a plurality of spouts of weldable plastics material, wherein the web is passed through a coater (32) in the form of a bath (45) of liquid containing a coating substance and then conveyed vertically from the bath (45) to a drier (34), the rate of feed of the web and the concentration of coating substance in the liquid being selected to produce a coating of desired thickness. The method and apparatus are particularly applicable to the making of a container of a plastics material which is weldable but porous to certain gases and needs to be coated with a substance which reduces the permeability to gas, but is not itself readily susceptible to welding. After coating, the contacting internal surfaces of the two halves of a tube, which surfaces have not been coated and are still weldable, can be welded together and the web formed into a plurality of individual containers each having a spout.