Highly air permeable expanded polytetrafluoroethylene membranes and process for making them
US4902423A · kind A · utility
114Cited by
9References
7Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Feb 2, 1989 |
| Grant date | Feb 20, 1990 |
| Priority date | — |
| Expiry date | Feb 2, 2009 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08J2327/18
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
A thin, low density porous polytetrafluoroethylene membrane having very large pores and heretofore unknown high air permeabilities is described. The membrane is produced by a particular series of longitudinal and transverse stretching steps carried out under particular conditions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.