Gas separating composite membrane and process for producing the same
US5647894A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 7, 1995 |
| Grant date | Jul 15, 1997 |
| Priority date | — |
| Expiry date | Jun 7, 2015 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S55/05
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
A gas separating composite membrane comprising two types of polyimide resin layers having different molecular structures and each having solubility in an organic solvent different from each other, the two layers being laminated being substantially independent or via a mixed layer, the first polyimide resin layer comprising a porous polyimide supporting membrane having a nitrogen gas permeation flux density at 25.degree. C. of at least 2 Nm.sup.3 /m.sup.2 /h/atm., and the second polyimide resin layer, which contributes to a gas separating performance comprising a fluorine-containing polyimide thin film containing at least three fluorine atoms in a repeating molecular structure unit which constructs the second polyimide resin layer has a very high gas permeation flux density while maintaining a high gas permeability, excels in heat resistance and chemical resistance, and satisfies a practical use in terms of cost.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.