Preparation of polycarbonate having reduced cyclic carbonate oligomer content
US4789730A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 5, 1986 |
| Grant date | Dec 6, 1988 |
| Priority date | — |
| Expiry date | Jun 5, 2006 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08G64/24
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
The present invention is directed to a continuous process which removes the 1 to 3% cyclic oligomers formed in the polycarbonate process and after hydrolysis of the oligomers recycles the resulting monomer for use in the reaction forming the polycarbonates. To remove the cyclic oligomers to a level so as to produce an improved polycarbonate product and to recover the oligomers in an economical manner for recycling in a continuous process, the selection of a solvent is unique and essential to achieve the continuous process. The solvent for the cyclic oligomers must be immiscible with water, must not react with an alkali and have a cohesive energy density of less than 90.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.