Method for preparation of copolyorganosiloxanecarbonates of high clarity
US6870013B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 8, 2003 |
| Grant date | Mar 22, 2005 |
| Priority date | — |
| Expiry date | Aug 8, 2023 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08G77/80
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
Copolyorganosiloxanecarbonates are prepared by first preparing an oligomeric aromatic polycarbonate, such as an oligomeric bisphenol A polycarbonate, in the presence of a tertiary amine as the only catalyst species; contacting the oligomeric polycarbonate mixture with a polyorganosiloxane bis(aryl)chloroformate, such as the bischloroformate of hydroxy-terminated eugenol polydimethylsiloxane; and introducing phosgene and/or chain termination agent either continuously or in stages. A feature of the process is the presence of dihydroxyaromatic compound in only one charge, at the beginning. The products have excellent physical properties, including transparency.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.