Process for producing porous aromatic polyimide membranes
US4474662A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 13, 1982 |
| Grant date | Oct 2, 1984 |
| Priority date | — |
| Expiry date | Apr 13, 2002 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08J2379/08
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
A porous membrane of an aromatic polyimide having an enhanced permeability of a gas or liquid is produced by a process comprising the steps of PA1 (1) preparing a dope solution of 3 to 30% by weight of an aromatic polyimide in a mixed solvent of (A) 100 parts by weight of a base solvent capable of dissolving 5% by weight or more of the polymeric acid and of evaporating at 30.degree. C. to 400.degree. C. and (B) 5 to 150 parts by weight of an additional liquid not capable of dissolving 3% by weight or more of the polyamic acid and capable of evaporating at a smaller evaporating rate than that of the base solvent at the above-mentioned evaporating temperature; PA1 (2) forming a thin layer of the dope solution at 0.degree. C. to 120.degree. C.; and PA1 (3) heating the dope solution layer at 30.degree. C. to 400.degree. C. so as to evaporate off the mixed solvent and to convert the polyamic acid to the corresponding polyimide.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.