Coextrustion apparatus, methods, and related films and packages
US5284687A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 15, 1991 |
| Grant date | Feb 8, 1994 |
| Priority date | — |
| Expiry date | Aug 15, 2011 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/3192
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
Apparatus and method for fabricating films, especially films containing vinylidene chloride copolymer, wherein the process is susceptible of continued operation over an extended period of time greater than a few days. The process typically can operate for at least 2 weeks between shut downs for cleaning the die. The apparatus comprises a coextrusion feedblock 20 in combination with an annular extrusion die 10 having a crosshead mandrel 11, and means for conveying the exit stream 24 from the feedblock to the die. The particular apparatus combination especially reduces the rate of carbon buildup in the extrusion apparatus during extrusion of VDC-copolymer, such that the extrusion process can be operated for a longer time between shutdowns for cleaning and maintenance of the die. The invention further includes novel tubular films 32 made with the apparatus and methods of the invention, and packages made from the films. In general, the method of the invention produces tubular films having more layers than the annular extrusion die has annular orifices.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.