Coextrusion of multilayer articles using protective boundary layers and apparatus therefor
US5269995A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 2, 1992 |
| Grant date | Dec 14, 1993 |
| Priority date | — |
| Expiry date | Oct 2, 2012 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29L2009/00
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A process and apparatus for the coextrusion of a multilayer polymeric body is provided which incorporates protective boundary layers into the body, protecting the layers from instability and breakup during layer formation and multiplication. The process includes the steps of providing at least first and second streams of heat plastified extrudable thermoplastic material which are combined to form a composite stream having the first substreams and second substreams interdigitated. A third stream of heat plastified thermoplastic material is supplied to the exterior surfaces of the composite stream to form protective boundary layers adjacent the walls of the coextrusion apparatus through which the heat plastified polymer streams pass. Layer instability and breakup are avoided using process conditions which would otherwise adversely affect the optical and/or mechanical properties of the articles which are formed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.