Apparatus for multilayer coextrusion of sheet or film

• US 3,884,606 A
• Filed: 06/12/1973
• Issued: 05/20/1975
• Est. Priority Date: 10/01/1971
• Status: Expired due to Term

• Current Assignee: Walter J. Schrenk
• Original Assignee: Walter J. Schrenk
• Inventors: Schrenk, Walter J.
• Primary Examiner(s): Annear, R. Spencer
• Application Number:
  US05/369,372
• Time in Patent Office: 707 Days
• Field of Search: 425/131,382 264/171
• US Class Current: 425/133.5
• CPC Class Codes: B29C 48/08 flexible, e.g. films
• CPC Class Codes: B29C 48/19 the layers being joined at their edges
• CPC Class Codes: B29C 48/21 the layers being joined at their surfaces
• CPC Class Codes: B29C 48/307 specially adapted for bringing together components, e.g. melts within the die

Abstract

Multilayer coextrusion method and apparatus are shown which provide a relatively easily obtained symmetry control of the layer thickness which is particularly suitable when the desired laminate contains many layers.

Claims

1. An apparatus for the preparation of a multilayer film or sheet, the apparatus comprising a body, the body defining at least a first polymer entrance passage, a first plenum in communication with the first polymer passage, a stream dividing means to divide material flowing from the first passage into a plurality of first substreams, second polymer receiving means in operative communication with a second plenum, the second plenum discharging to the dividing means which divides the second stream into a plurality of second substreams and interdigitates the plurality of second substreams with the first substreams, the dividing means being in operative communication with a third or composite stream receiving plenum, the composite stream comprising the combined first and second substreams, a third plenum discharge passage in operative communication with the third plenum and adapted to receive the composite stream from the third plenum, the discharge means being in combination with a die having a generally slot-like extrusion orifice, the discharge passage having a first or receiving end and a second or discharge end, the improvement which comprises disposing the discharge portion of the stream dividing means in an arcuate manner to form an arc of a circle wherein the discharge portion is generally equidistant from the discharge end of the third plenum discharge passage.

2. The apparatus of claim 1 including a third polymer receiving means in communication with a third polymer receiving plenum, the third polymer receiving plenum discharging to the stream dividing means to provide a plurality of third substreams which are interdigitated with the first and second substreams.

3. The apparatus of claim 1 in operative combination with means to supply first and second streams of heat plastified synthetic resinous material.