Branched polycarbonates and processes for producing the same
US7696297B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 30, 2008 |
| Grant date | Apr 13, 2010 |
| Priority date | — |
| Expiry date | Oct 17, 2028 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08G64/14
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
Methods for making a branched polycarbonate are disclosed. An interfacial mixture comprising water, a substantially water-immiscible organic solvent, a dihydroxy compound, a polyhydric branching agent, an endcapping agent, a catalyst, and a base is formed. The base and the branching agent are dissolved in the mixture before the dihydroxy compound is added, and the interfacial mixture has a basic pH. The mixture is reacted by adding a carbonate precursor to the mixture while maintaining the pH between about 8 and about 10 to form the branched polycarbonate. The resulting branched polycarbonates may contain more than 1.5 mole % of the THPE; have residual chloride content of 20 ppm or less; and a weight average molecular weight of about 55,000 or less. They may also be highly transparent.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.