Process for the production of foamed polyolefin sheets
US5281377A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 13, 1992 |
| Grant date | Jan 25, 1994 |
| Priority date | — |
| Expiry date | Oct 13, 2012 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29L2023/001
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A foamed polyolefin sheet is formed by extruding a molten polyolefin resin, which contains a blowing agent, into a low-pressure zone through an annular die provided at an end of the extruder to form a foamed tubular body, bringing the foamed tubular body into contact with a peripheral surface of a cylindrical cooling device to cool the foamed tubular body and then slitting the thus-cooled foamed tubular body and then slitting the thus-cooled foamed tubular body in the direction of extrusion to open same. The cylindrical cooling device is divided into an upstream section and at least one other spaced downstream sections. The internal pressure of the foamed tubular body is increased to from about 5.times.10.sup.-4 to 3.times.10.sup.-2 kg/cm.sup.2 (G) between the die and the upstream section of the cylindrical cooling device and also between at least two adjacent sections of the cylindrical cooling device to apply tension to the foamed tubular body at the inner wall and prevent the formation of corrugations.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.