Process and apparatus for forming a composite foamed polymeric sheet structure having comparatively high density skin layers and a comparatively low density core layer
US4456571A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 13, 1982 |
| Grant date | Jun 26, 1984 |
| Priority date | — |
| Expiry date | Dec 13, 2002 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S264/05
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A method and apparatus for producing a foamed polymeric sheet having comparatively high density skin layers. Molten polymer containing a foaming agent is extruded from a die into a post-extrusion region defined by the die and a spaced pair of rotating chill rolls which are spaced from the die. The post-extrusion region is maintained at a pressure sufficient to at least inhibit expansion of the foamable molten polymer through the use of cooled sealing elements which occupy a substantial portion of the space between the die and the chill rolls, and are spaced from the chill rolls. The rolls and the sealing elements are cooled so that foamable molten polymer in the space between the sealing elements and the rolls becomes solidified, completing the seal. The chill rolls are maintained at a temperature below the temperature of the molten polymer to aid the skin formation on the surfaces of the polymer. If desired, the polymer can pass directly from the chill rolls into a water bath.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.