Polyolefin foam beads having high density crust and method for manufacturing the same
US6476088B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 16, 2001 |
| Grant date | Nov 5, 2002 |
| Priority date | — |
| Expiry date | Apr 28, 2021 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08J2323/02
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
Polyolefin foam bead having a high-density crust and a method for manufacturing the same are disclosed. The novel polyolefin foam bead having an surface layer (crust) which is higher in density than its inner structure can be manufactured by the method comprised of impregnating a polyolefin resin with a forming agent by stirring the mixture of the polyolefin resin particles, water and the foaming agent in a pressure vessel under heat, followed by diffusing out the foaming agent from the surface layer of the resin particle to decrease the concentration of the foaming agent in the surface layer. Thereafter, the polyolefin resin is foamed by discharging the resin particles to low pressure environment.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.