Interfacial copolyestercarbonate method using catalyst comprising hexaalkylguanidinium salt and tertiary amine
US5807965A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 23, 1997 |
| Grant date | Sep 15, 1998 |
| Priority date | — |
| Expiry date | Dec 23, 2017 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08G63/64
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
The level of anhydride linkages in copolyestercarbonates is decreased by preparing the copolyestercarbonate interfacially in a two-step method from at least one dihydroxyaromatic compound and at least one dicarboxylic acid. The first step is conducted at a pH in the range of about 4.5-9.5, employing the combination of a hexaalkylguanidinium salt as a phase transfer catalyst and a tertiary amine such as triethylamine. The proportion of the phase transfer catalyst and tertiary amine are usually in the range of about 1-5 and about 0.01-5.0 mole percent, respectively, based on total dihydroxyaromatic compound and dicarboxylic acid employed. In the second phosgenation step, the pH is raised to at least 10 and a stoichiometric phosgene excess of at least 5% is introduced.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.