Process for producing pre-foamed particles of polyolefin resin
US4436840A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 21, 1982 |
| Grant date | Mar 13, 1984 |
| Priority date | — |
| Expiry date | Sep 21, 2002 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S264/09
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
In a process for producing pre-foamed particles of a polyolefin resin which comprises impregnating a volatile blowing agent into particles of a polyolefin resin while dispersing the resin particles and the blowing agent in a dispersing medium under heat in a closed vessel, opening one end of the vessel and releasing the resin particles and the dispersing medium simultaneously into an atmosphere kept at a lower pressure than the inside pressure of the vessel; the improvement wherein the pressure of the inside of the vessel after opening its one end is maintained at a substantially constant pressure which is at least 0.7 times the vapor pressure of the blowing agent before opening the end of the vessel.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.