Melt polycarbonate catalyst systems
US6323304A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 12, 2001 |
| Grant date | Nov 27, 2001 |
| Priority date | — |
| Expiry date | Jan 12, 2021 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08G64/307
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
This invention provides a method for preparing polycarbonates, which utilizes polycondensation catalysts of the formula A.sub.x.sup.+ MF.sub.6.sup.-x, wherein A is an alkali metal or alkaline earth cation; M is a transition metal of group IVA or VA, or M is a p-block metal of group IIIB, IVB or VB; and x is 1, 2, or 3. We have found that this new class of catalysts provide excellent polymerization rates for the preparation of Bisphenol A polycarbonate from the melt polymerization of diphenyl carbonate and Bisphenol A. Moreover, the catalysts of the invention were found to be very selective in substantially reducing the level of branching side reaction, i.e., formation of Fries product, normally associated with the melt polycarbonate process.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.