Method of polycarbonate preparation
US6870025B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 23, 2002 |
| Grant date | Mar 22, 2005 |
| Priority date | — |
| Expiry date | Feb 14, 2023 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08L69/00
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
Polycarbonates containing low or undetectable levels of Fries rearrangement products and comprising repeat units derived from one or more of resorcinol, hydroquinone, methylhydroquinone, bisphenol A, and 4,4′-biphenol have been prepared by the melt reaction of one or more of the aforementioned dihydroxy aromatic compounds with an ester-substituted diaryl carbonate such as bis-methyl salicyl carbonate. Low, or in many instances undetectable, levels of Fries rearrangement products are found in the product polycarbonates obtained as the combined result of a highly effective catalyst system which suppresses the Fries reaction and the use of lower melt polymerization temperatures relative to temperatures required for the analogous polymerization reactions using diphenyl carbonate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.