Coextrusion process for producing multiple layered thermoplastic pipe
US4499041A · kind A · utility
7Cited by
11References
5Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | May 23, 1983 |
| Grant date | Feb 12, 1985 |
| Priority date | — |
| Expiry date | May 23, 2003 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29C48/32
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A process is disclosed for the coextrusion of a multi-layered tube whereby at least one stream of molten polymer from a single-screw extruder is passed through a die; wherein the stream is divided into two concentric streams which are balanced by varying the area of a restrictor orifice placed in the central stream. Spider lines in the outer molten stream are eliminated by the use of a second restrictor means used downstream of an open chamber for reuniting the melt, which chamber is downstream of the spider legs.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.