Process for forming asymmetric gas separation membranes having graded density skins
US4871494A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 6, 1987 |
| Grant date | Oct 3, 1989 |
| Priority date | — |
| Expiry date | Jul 6, 2007 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB01D2325/022
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
A process for forming high free volume, asymmetric gas separation membranes having graded density skins and macrovoid-free morphology from a solvent system comprising a Lewis acid, Lewis base, and a Lewis acid:base complex which dissolve hydrophobic polymers. The dopes have high total solids, high viscosity and low coagulation (g) values which enhance rapid gelation without the formation of macrovoids and which minimize densification. The dope solvent system complexes are readily disassociated by the coagulation medium and the component molecules are miscible in the medium which provides for rapid desolvation of the formed membrane thus providing a membrane having low residual solvent retention.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.