Production of foamed polymer structures
US4822537A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 20, 1988 |
| Grant date | Apr 18, 1989 |
| Priority date | — |
| Expiry date | Jun 20, 2008 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S521/915
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
Described are ways of improving the yields of specification grade polyimide on a consistent basis from one run to the next, by use of improved microwave-based foaming processes. In one such process, during the application of the microwave radiation, the body of polyimide precursor and of the foam structure as it is developing therefrom are maintained under a substantially vapor-impermeable microwave-compatible shroud that does not substantially restrict or impede development of the foam structure; and the microwave radiation is directed upon the top, sides and ends of the body of polyimide precursor and of the foam structure as it is developing, but the extent to which such radiation impinges upwardly into the bottom of said body and said foam structure is curtailed, preferably by means of a metallic shield located below the precursor and developing foam structure. Mechanism by which the shields and shrouds function to provide the improvements of the process are discussed, and methods based thereon are set forth.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.