Method and extrusion head for the production of multilayered flat films or sheets, bands or webs, conveyor belts and the like, from thermoplastic synthetic materials

摘要

Multi-layer composite films, bands &c., are produced by feeding synthetic organic thermoplastic film-forming material by means of screw extruders 7 and 8 (Figs. 1 and 2) to an extrusion head 1 provided with ducts 4 and 5 which extend parallel to and communicate with the extrusion orifice 6 having the form of an elongated slot formed by lips 9 and 10 which are mounted on an anterior plate 3 and are adjustable by means of set screws 11. The rate at which the material flows from the ducts 4 and 5 to the extrusion orifice 6 is controlled by means of the adjustable metering strips 12 and 13. When it is desired to coat a web of fabric on both sides with a film or coating of the film-forming material the web of fabric is caused to pass through a duct 17 of slot-shaped cross-section in a member 16 mounted in the rear plate 2 and through the horizontal centre plane of the extrusion orifice p 6. If a 2 layer of 2 ply film is to be produced without any intermediate reinforcement web of fabric or other material the member or web-guide 16 is substituted by a member which is not provided with a duct and so shaped as to function as a mandrel.