Co-extrusions methods
US5143677A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 28, 1989 |
| Grant date | Sep 1, 1992 |
| Priority date | — |
| Expiry date | Dec 28, 2009 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB32B2553/00
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
Apparatus and method for fabricating films and packages, especially films and packages containing a layer of vinylidene chloride copolymer. The preferred apparatus includes a coextrusion feedblock (20) in combination with an annular extrusion die (10) having an internal crosshead mandrel (11), and intervening spacing means for conveying the melt stream (24) from the feedblock to the die. The mandrel (11) has a cross-head groove (14), whose preferred design resembles elements of a rectangle. The inner surface of the outer die wall (19) preferably has an offset portion, including one of a pair of ramps (33A, 33B) traversed by the melt stream (24) as it leaves the groove. The die (10) maintains the melt stream in a single basic shape as the melt stream traverses the die. The VDC copolymer is shielded from the equipment surfaces beyond the VDC copolymer extruder. Equipment surfaces beyond the VDC copolymer extruder are protected from the VDC copolymer. The effective shielding enables use of a die (10) greater than 85 cm. circumference at its exit (31).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.