Carbonic acid diester, aromatic polycarbonate and facilities, and preparation thereof
US6323302A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 14, 1999 |
| Grant date | Nov 27, 2001 |
| Priority date | — |
| Expiry date | Dec 14, 2019 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08G64/307
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
Aromatic polycarbonate having a reduced discoloration and improved heat stability, hue, etc. is provided by keeping a pressure in a raw material melting vessel and the linear velocity of a gas in a transporting piping in a specific range, keeping the concentration of a nitrogen-containing basic compound in a specific range, recycling a byproduct containing specific amounts of impurities, suppressing the amounts of a nitrogen-containing basic compound, metallic elements and a silicic acid derivative in the carbonic acid diester at specific values or less, prescribing the material quality of the reaction facilities, and/or forming an oxide layer at the inner wall surfaces of the reaction facilities.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.