Method for preparing aromatic bischloroformate compositions and polycarbonates
US5580951A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 25, 1994 |
| Grant date | Dec 3, 1996 |
| Priority date | — |
| Expiry date | Aug 25, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/2534
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
Bischloroformate oligomer compositions are prepared by passing phosgene into a heterogeneous aqueous-organic mixture containing at least one dihydroxyaromatic compound, with simultaneous introduction of a base at a rate to maintain a specific pH range and to produce a specific volume ratio of aqueous to organic phase. By this method, it is possible to employ a minimum amount of phosgene. The reaction may be conducted batchwise or continuously. The bischloroformate composition may be employed for the preparation of cyclic polycarbonate oligomers or linear polycarbonate, and linear polycarbonate formation may be integrated with bischloroformate composition formation in a batch or continuous process.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.