Coextrusion process and apparatus for manufacturing multi-layered flat films of thermoplastic materials

US4426344A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Peter Dinter · Obermoschel, DE
• Andreas Kolbe · Berlin, DE

Key dates

• Filing date: Jul 6, 1981
• Grant date: Jan 17, 1984
• Expiry date: Jul 6, 2001

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/24537
• WIPO field: Other special machines
• WIPO sector: Mechanical engineering

Abstract

Disclosed is a process for producing a multiple-layered sheet of film comprising at least two thermoplastic materials by coextrusion through a slot die, comprising the steps of heat plastifying a first, second, third and fourth thermoplastic material; joining a stream of the first heat plastified thermoplastic material and a stream of the second heat plastified thermoplastic material to form a first combined stream having a generally rectangular cross-section and having an upper layer of the first thermoplastic material and a lower layer of the second thermoplastic material mechnically anchored together by means of profiles formed on the contact surfaces of the two layers; joining a stream of the third heat plastified thermoplastic material and a stream of the fourth heat plastified thermoplastic material to form a similar second combined stream, reducing the width of the first and second combined stream; joining the first and second combined streams in edge-to-edge fashion in a single plane to form a composite stream; introducing the composite stream into the inlet channel of the slot die; coextruding the composite stream through the slot die to form a multiple layer film or sheet…