Polycarbonates containing low levels of methyl salicylate prepared by a melt polymerization in a reactive extruder
US7485695B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 6, 2006 |
| Grant date | Feb 3, 2009 |
| Priority date | — |
| Expiry date | Mar 17, 2027 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29K2069/00
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
Polycarbonate is prepared by reactive extrusion on a reactive extruder. A method incorporates the steps of introducing a polycarbonate oligomer, an activated carbonate, and a transesterification catalyst to the extruder through a feed section. The extruder has a feed section, a polycarbonate exit section, and a reaction section between the feed section and the polycarbonate exit section. The reaction section has one or more devolatilization units, wherein each devolatilization unit incorporates an array of vent-conveying sections and conveying sections arranged in a configuration of: (C V C)x(V)n, and/or (V C V)x(C)n. (V) is a vent-conveying section, (C) is a conveying section, x is 1 or more, and n is 1 or 0. The extruder screw in the vent-conveying sections and the conveying sections in each devolatilization unit have conveying elements or conveying elements and mixing elements and no elements that create a melt seal in the devolatilization unit. The method further includes the step of extruding the reaction components at a temperature in a range between 100° C. and 500° C., wherein during the extrusion of the reaction components, activated carbonate residue is removed through th…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.